heur_scheduler.c

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/*         SCIP --- Solving Constraint Integer Programs                      */
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/**@file   heur_scheduler.c
 * @ingroup DEFPLUGINS_HEUR
 * @brief  Adaptive heuristic to schedule LNS and diving heuristics
 * @author Gregor Hendel
 * @author Antonia Chmiela
 */
 
/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
 
#include "blockmemshell/memory.h"
#include "scip/cons_linear.h"
#include "scip/heur_scheduler.h"
#include "scip/heuristics.h"
#include "scip/pub_bandit_epsgreedy.h"
#include "scip/pub_bandit_exp3.h"
#include "scip/pub_bandit_exp3ix.h"
#include "scip/pub_bandit.h"
#include "scip/pub_bandit_ucb.h"
#include "scip/pub_cons.h"
#include "scip/pub_event.h"
#include "scip/pub_heur.h"
#include "scip/pub_message.h"
#include "scip/pub_misc.h"
#include "scip/pub_misc_select.h"
#include "scip/pub_sol.h"
#include "scip/pub_var.h"
#include "scip/scip_bandit.h"
#include "scip/scip_branch.h"
#include "scip/scip_cons.h"
#include "scip/scip_copy.h"
#include "scip/scip_event.h"
#include "scip/scip_general.h"
#include "scip/scip_heur.h"
#include "scip/scip_lp.h"
#include "scip/scip_mem.h"
#include "scip/scip_message.h"
#include "scip/scip_nodesel.h"
#include "scip/scip_numerics.h"
#include "scip/scip_param.h"
#include "scip/scip_prob.h"
#include "scip/scip_randnumgen.h"
#include "scip/scip_sol.h"
#include "scip/scip_solve.h"
#include "scip/scip_solvingstats.h"
#include "scip/scip_table.h"
#include "scip/scip_timing.h"
#include "scip/scip_tree.h"
#include "scip/scip_var.h"
#include <string.h>
 
#if !defined(_WIN32) && !defined(_WIN64)
#include <strings.h> /*lint --e{766}*/ /* needed for strncasecmp() */
#endif
 
#define HEUR_NAME             "scheduler"
#define HEUR_DESC             "Adaptive heuristic to schedule LNS and diving heuristics"
#define HEUR_DISPCHAR         SCIP_HEURDISPCHAR_LNS
#define HEUR_PRIORITY         -30000
#define HEUR_FREQ             -1
#define HEUR_FREQOFS          0
#define HEUR_MAXDEPTH         -1
#define HEUR_TIMING           SCIP_HEURTIMING_AFTERNODE
#define HEUR_USESSUBSCIP      TRUE  /**< does the heuristic use a secondary SCIP instance? */
 
#define NNEIGHBORHOODS 9
#define DIVINGHEURS_INITIALSIZE 10
 
/*
 * limit parameters for sub-SCIPs
 */
#define DEFAULT_NODESQUOT        0.1
#define DEFAULT_NODESQUOTMIN     0.0
#define DEFAULT_NODESOFFSET      500LL
#define DEFAULT_NSOLSLIM         3
#define DEFAULT_MINNODES         50LL
#define DEFAULT_MAXNODES         500LL
#define DEFAULT_WAITINGNODES     0LL  /**< number of nodes since last incumbent solution that the heuristic should wait */
#define DEFAULT_INITLNSNODELIMIT 50
#define DEFAULT_INITDIVINGNODELIMIT 500LL
#define DEFAULT_TARGETNODEFACTOR 1.05
#define LRATEMIN                 0.01 /**<  lower bound for learning rate for target nodes and minimum improvement */
#define LPLIMFAC                 4.0
#define DEFAULT_INITDURINGROOT FALSE
#define DEFAULT_MAXCALLSSAMESOL  -1   /**< number of allowed executions of the heuristic on the same incumbent solution */
#define DEFAULT_HEURTIMELIMIT    60.0 /**< time limit for a single heuristic run */
 
/*
 * bandit algorithm parameters
 */
#define DEFAULT_BESTSOLWEIGHT  1
#define DEFAULT_BANDITALGO     'i'  /**< the default bandit algorithm: (u)pper confidence bounds, (e)xp.3, epsilon (g)reedy, exp.3-(i)x */
#define DEFAULT_RESETWEIGHTS   FALSE/**< should the bandit algorithms be reset when a new problem is read? */
#define DEFAULT_SUBSCIPRANDSEEDS FALSE /**< should random seeds of sub-SCIPs be altered to increase diversification? */
#define DEFAULT_FIXTOL         0.1  /**< tolerance by which the fixing rate may be missed without generic fixing */
#define DEFAULT_UNFIXTOL       0.1  /**< tolerance by which the fixing rate may be exceeded without generic unfixing */
#define DEFAULT_BETA           0.0  /**< default reward offset between 0 and 1 at every observation for exp3 */
#define DEFAULT_NSELECTIONS      5  /**< number of heuristics picked by the scheduler in one call (-1: number of controlled heuristics, 0: until new incumbent is found) */
 
/*
 * parameters to control variable fixing
 */
#define DEFAULT_USEREDCOST       TRUE  /**< should reduced cost scores be used for variable priorization? */
#define DEFAULT_USEPSCOST        TRUE  /**< should pseudo cost scores be used for variable priorization? */
#define DEFAULT_USEDISTANCES     TRUE  /**< should distances from fixed variables be used for variable priorization */
#define DEFAULT_USELOCALREDCOST FALSE /**< should local reduced costs be used for generic (un)fixing? */
 
/*
 * parameters for reward computation
 */
#define DEFAULT_EFFORTREWARDWEIGHT 0.2
#define DEFAULT_SOLREWARDWEIGHT 0.3
#define DEFAULT_QUALREWARDWEIGHT 0.3
#define DEFAULT_CONFLICTREWARDWEIGHT 0.2
 
/*
 * the following 3 parameters have been tuned by a simulation experiment
 * as described in the paper.
 */
#define DEFAULT_EPS            0.4685844   /**< increase exploration in epsilon-greedy bandit algorithm */
#define DEFAULT_ALPHA          0.0016      /**< parameter to increase the confidence width in UCB */
#define DEFAULT_GAMMA          0.07041455  /**< default weight between uniform (gamma ~ 1) and weight driven (gamma ~ 0) probability distribution for exp3 */
 
/*
 * parameters to control solve frequency for diving heuristics
 */
#define SOLVEFREQ_DECAY        0.75  /**< geometric decay for solving freq adjustments */
#define SOLVEFREQ_STARTINC     0.2   /**< initial increment value for solving frequency */
#define MAXSOLVEFREQ           0.3   /**< maximal solving frequency */
#define MINSOLVEFREQ           0.05  /**< minimal solving frequency */
 
/*
 * parameters to control variable fixing
 */
#define FIXINGRATE_DECAY         0.75  /**< geometric decay for fixing rate adjustments */
#define FIXINGRATE_STARTINC      0.2   /**< initial increment value for fixing rate */
#define DEFAULT_USESUBSCIPHEURS  FALSE /**< should the heuristic activate other sub-SCIP heuristics during its search?  */
#define DEFAULT_COPYCUTS         FALSE /**< should cutting planes be copied to the sub-SCIP? */
 
/* individual random seeds */
#define DEFAULT_SEED 113
#define MUTATIONSEED 121
#define CROSSOVERSEED 321
 
/* individual neighborhood parameters */
#define DEFAULT_MINFIXINGRATE_RENS 0.3
#define DEFAULT_MAXFIXINGRATE_RENS 0.9
#define DEFAULT_ACTIVE_RENS TRUE
//#define DEFAULT_PRIORITY_RENS 1.0
#define DEFAULT_PRIORITY_RENS -1100000
 
#define DEFAULT_MINFIXINGRATE_RINS 0.3
#define DEFAULT_MAXFIXINGRATE_RINS 0.9
#define DEFAULT_ACTIVE_RINS TRUE
//#define DEFAULT_PRIORITY_RINS 1.0
#define DEFAULT_PRIORITY_RINS -1101000
 
#define DEFAULT_MINFIXINGRATE_MUTATION 0.3
#define DEFAULT_MAXFIXINGRATE_MUTATION 0.9
#define DEFAULT_ACTIVE_MUTATION TRUE
//#define DEFAULT_PRIORITY_MUTATION 1.0
#define DEFAULT_PRIORITY_MUTATION -1103010
 
#define DEFAULT_MINFIXINGRATE_LOCALBRANCHING 0.3
#define DEFAULT_MAXFIXINGRATE_LOCALBRANCHING 0.9
#define DEFAULT_ACTIVE_LOCALBRANCHING TRUE
//#define DEFAULT_PRIORITY_LOCALBRANCHING 1.0
#define DEFAULT_PRIORITY_LOCALBRANCHING -1102000
 
#define DEFAULT_MINFIXINGRATE_PROXIMITY 0.3
#define DEFAULT_MAXFIXINGRATE_PROXIMITY 0.9
#define DEFAULT_ACTIVE_PROXIMITY TRUE
//#define DEFAULT_PRIORITY_PROXIMITY 1.0
#define DEFAULT_PRIORITY_PROXIMITY -2000000
 
#define DEFAULT_MINFIXINGRATE_CROSSOVER 0.3
#define DEFAULT_MAXFIXINGRATE_CROSSOVER 0.9
#define DEFAULT_ACTIVE_CROSSOVER TRUE
//#define DEFAULT_PRIORITY_CROSSOVER 1.0
#define DEFAULT_PRIORITY_CROSSOVER -1104000
 
#define DEFAULT_MINFIXINGRATE_ZEROOBJECTIVE 0.3
#define DEFAULT_MAXFIXINGRATE_ZEROOBJECTIVE 0.9
#define DEFAULT_ACTIVE_ZEROOBJECTIVE TRUE
//#define DEFAULT_PRIORITY_ZEROOBJECTIVE 1.0
#define DEFAULT_PRIORITY_ZEROOBJECTIVE 100
 
#define DEFAULT_MINFIXINGRATE_DINS 0.3
#define DEFAULT_MAXFIXINGRATE_DINS 0.9
#define DEFAULT_ACTIVE_DINS TRUE
//#define DEFAULT_PRIORITY_DINS 1.0
#define DEFAULT_PRIORITY_DINS -1105000
 
#define DEFAULT_MINFIXINGRATE_TRUSTREGION 0.3
#define DEFAULT_MAXFIXINGRATE_TRUSTREGION 0.9
#define DEFAULT_ACTIVE_TRUSTREGION FALSE
//#define DEFAULT_PRIORITY_TRUSTREGION 1.0
#define DEFAULT_PRIORITY_TRUSTREGION -1102010
 
 
#define DEFAULT_NSOLS_CROSSOVER 2 /**< parameter for the number of solutions that crossover should combine */
#define DEFAULT_NPOOLSOLS_DINS  5 /**< number of pool solutions where binary solution values must agree */
#define DEFAULT_VIOLPENALTY_TRUSTREGION 100.0  /**< the penalty for violating the trust region */
 
/* event handler properties */
#define EVENTHDLR_NAME         "Scheduler"
#define EVENTHDLR_DESC         "LP event handler for " HEUR_NAME " heuristic"
#define SCIP_EVENTTYPE_SCHEDULER (SCIP_EVENTTYPE_LPSOLVED | SCIP_EVENTTYPE_SOLFOUND | SCIP_EVENTTYPE_BESTSOLFOUND)
 
/* properties of the scheduler neighborhood statistics table */
#define TABLE_NAME_NEIGHBORHOOD                  "scheduler"
#define TABLE_DESC_NEIGHBORHOOD                  "scheduler heuristics statistics"
#define TABLE_POSITION_NEIGHBORHOOD              12500                  /**< the position of the statistics table */
#define TABLE_EARLIEST_STAGE_NEIGHBORHOOD        SCIP_STAGE_TRANSFORMED /**< output of the statistics table is only printed from this stage onwards */
 
/*
 * additional neighborhood data structures
 */
 
 
typedef struct data_crossover DATA_CROSSOVER; /**< crossover neighborhood data structure */
 
typedef struct data_mutation DATA_MUTATION; /**< mutation neighborhood data structure */
 
typedef struct data_dins DATA_DINS; /**< dins neighborhood data structure */
 
typedef struct data_trustregion DATA_TRUSTREGION; /**< trustregion neighborhood data structure */
 
typedef struct NH_FixingRate NH_FIXINGRATE; /** fixing rate data structure */
 
typedef struct SolveFreq SOLVEFREQ; /** diving heuristic solving frequency data structure */
 
typedef struct Heur_Stats HEUR_STATS; /**< heuristic statistics data structure */
 
typedef struct Nh NH;             /**< neighborhood data structure */
 
typedef struct Diving_Heur DIVING_HEUR; /**< diving heuristic data structure */
 
/*
 * variable priorization data structure for sorting
 */
typedef struct VarPrio VARPRIO;
 
/** callback to collect variable fixings of neighborhood */
 #define DECL_VARFIXINGS(x) SCIP_RETCODE x ( \
   SCIP*                 scip,               /**< SCIP data structure */                     \
   NH*                   neighborhood,       /**< neighborhood data structure */         \
   SCIP_VAR**            varbuf,             /**< buffer array to collect variables to fix */\
   SCIP_Real*            valbuf,             /**< buffer array to collect fixing values */   \
   int*                  nfixings,           /**< pointer to store the number of fixings */  \
   SCIP_RESULT*          result              /**< result pointer */                          \
   )
 
/** callback for subproblem changes other than variable fixings
 *
 *  this callback can be used to further modify the subproblem by changes other than variable fixings.
 *  Typical modifications include restrictions of variable domains, the formulation of additional constraints,
 *  or changed objective coefficients.
 *
 *  The callback should set the \p success pointer to indicate whether it was successful with its modifications or not.
 */
#define DECL_CHANGESUBSCIP(x) SCIP_RETCODE x (  \
   SCIP*                 sourcescip,         /**< source SCIP data structure */\
   SCIP*                 targetscip,         /**< target SCIP data structure */\
   NH*                   neighborhood,       /**< neighborhood data structure */\
   SCIP_VAR**            subvars,            /**< array of targetscip variables in the same order as the source SCIP variables */\
   int*                  ndomchgs,           /**< pointer to store the number of performed domain changes */\
   int*                  nchgobjs,           /**< pointer to store the number of changed objective coefficients */ \
   int*                  naddedconss,        /**< pointer to store the number of additional constraints */\
   SCIP_Bool*            success             /**< pointer to store if the sub-MIP was successfully adjusted */\
   )
 
/** optional initialization callback for neighborhoods when a new problem is read */
#define DECL_NHINIT(x) SCIP_RETCODE x (                                          \
   SCIP*                 scip,               /**< SCIP data structure */         \
   NH*                   neighborhood        /**< neighborhood data structure */ \
   )
 
/** deinitialization callback for neighborhoods when exiting a problem */
#define DECL_NHEXIT(x) SCIP_RETCODE x ( \
   SCIP*                 scip,               /**< SCIP data structure */         \
   NH*                   neighborhood        /**< neighborhood data structure */ \
   )
 
/** deinitialization callback for neighborhoods before SCIP is freed */
#define DECL_NHFREE(x) SCIP_RETCODE x (      \
   SCIP*                 scip,               /**< SCIP data structure */         \
   NH*                   neighborhood        /**< neighborhood data structure */ \
   )
 
/** callback function to return a feasible reference solution for further fixings
 *
 *  The reference solution should be stored in the \p solptr.
 *  The \p result pointer can be used to indicate either
 *
 *  - SCIP_SUCCESS or
 *  - SCIP_DIDNOTFIND
 */
#define DECL_NHREFSOL(x) SCIP_RETCODE x (                                       \
   SCIP*                 scip,               /**< SCIP data structure */  \
   NH*                   neighborhood,       /**< neighborhood data structure */ \
   SCIP_SOL**            solptr,             /**< pointer to store the reference solution */ \
   SCIP_RESULT*          result              /**< pointer to indicate the callback success whether a reference solution is available */ \
   )
 
/** callback function to deactivate neighborhoods on problems where they are irrelevant */
#define DECL_NHDEACTIVATE(x) SCIP_RETCODE x (\
   SCIP*                 scip,               /**< SCIP data structure */  \
   SCIP_Bool*            deactivate          /**< pointer to store whether the neighborhood should be deactivated (TRUE) for an instance */ \
   )
 
/** sub-SCIP status code enumerator */
enum HistIndex
{
   HIDX_OPT              = 0,                /**< sub-SCIP was solved to optimality  */
   HIDX_USR              = 1,                /**< sub-SCIP was user interrupted */
   HIDX_NODELIM          = 2,                /**< sub-SCIP reached the node limit */
   HIDX_STALLNODE        = 3,                /**< sub-SCIP reached the stall node limit */
   HIDX_INFEAS           = 4,                /**< sub-SCIP was infeasible */
   HIDX_SOLLIM           = 5,                /**< sub-SCIP reached the solution limit */
   HIDX_OTHER            = 6                 /**< sub-SCIP reached none of the above codes */
};
typedef enum HistIndex HISTINDEX;
#define NHISTENTRIES 7
 
 
/** statistics for heuristics */
struct Heur_Stats
{
   SCIP_Real             oldupperbound;      /**< upper bound before the heuristic started */
   SCIP_Real             newupperbound;      /**< new upper bound for allrewards mode to work correctly */
   int                   nruns;              /**< number of runs of a heuristic */
   int                   nrunsbestsol;       /**< number of runs that produced a new incumbent */
   SCIP_Longint          nsolsfound;         /**< the total number of solutions found */
   SCIP_Longint          nbestsolsfound;     /**< the total number of improving solutions found */
   SCIP_CLOCK*           setupclock;         /**< clock for setup time */
   SCIP_CLOCK*           execclock;        /**< clock for the heuristic execution */
   /* for diving */
   SCIP_Longint          nbacktracks;        /**< total number of used backtracks */
   SCIP_Longint          nconflicts;         /**< total number of conflict constraints generated */
   SCIP_Longint          nprobnodes;         /**< total number of probing nodes used */
   int                   divingdepth;        /**< depth of last dive */
   /* for LNS */
   SCIP_Longint          usednodes;          /**< total number of used nodes */
   int                   nfixings;           /**< the number of fixings in one run */
   int                   statushist[NHISTENTRIES]; /**< array to count sub-SCIP statuses */
};
 
 
/** fixing rate data structure to control the amount of target fixings of a neighborhood */
struct NH_FixingRate
{
   SCIP_Real             minfixingrate;      /**< the minimum fixing rate */
   SCIP_Real             targetfixingrate;   /**< the current target fixing rate */
   SCIP_Real             increment;          /**< the current increment by which the target fixing rate is in-/decreased */
   SCIP_Real             maxfixingrate;      /**< the maximum fixing rate */
};
 
/** solve frequency for diving heuristics */
struct SolveFreq
{
   SCIP_Real             minsolvefreq;       /**< the minimum solve frequency */
   SCIP_Real             currentsolvefreq;   /**< the current solve frequency */
   SCIP_Real             increment;          /**< the current increment by which the solve frequency is in-/decreased */
   SCIP_Real             maxsolvefreq;       /**< the maximum solve frequency */
};
 
/** neighborhood data structure with callbacks, statistics, fixing rate */
struct Nh
{
   char*                 name;               /**< the name of this neighborhood */
   NH_FIXINGRATE         fixingrate;         /**< fixing rate for this neighborhood */
   HEUR_STATS            stats;              /**< statistics for this neighborhood */
   int                   nodelimit;          /**< nodelimit for next execution */
   DECL_VARFIXINGS       ((*varfixings));    /**< variable fixings callback for this neighborhood */
   DECL_CHANGESUBSCIP    ((*changesubscip)); /**< callback for subproblem changes other than variable fixings */
   DECL_NHINIT           ((*nhinit));        /**< initialization callback when a new problem is read */
   DECL_NHEXIT           ((*nhexit));        /**< deinitialization callback when exiting a problem */
   DECL_NHFREE           ((*nhfree));        /**< deinitialization callback before SCIP is freed */
   DECL_NHREFSOL         ((*nhrefsol));      /**< callback function to return a reference solution for further fixings, or NULL */
   DECL_NHDEACTIVATE     ((*nhdeactivate));  /**< callback function to deactivate neighborhoods on problems where they are irrelevant, or NULL if it is always active */
   SCIP_Bool             active;             /**< is this neighborhood active or not? */
   SCIP_Real             priority;           /**< positive call priority to initialize bandit algorithms */
   int                   rootnodepriority;   /**< heuristic's priority for call at rootnode */
   union
   {
      DATA_MUTATION*     mutation;           /**< mutation data */
      DATA_CROSSOVER*    crossover;          /**< crossover data */
      DATA_DINS*         dins;               /**< dins data */
      DATA_TRUSTREGION*  trustregion;        /**< trustregion data */
   }                     data;               /**< data object for neighborhood specific data */
};
 
/** diving heuristic data structure with statistics and diveset */
struct Diving_Heur
{
   SCIP_DIVESET*         diveset;            /**< publicly available divesets from diving heuristics */
   HEUR_STATS*           stats;              /**< statistics for this diveset */
   SCIP_Longint          nodelimit;          /**< node limit of diving heuristics for next execution */
   SOLVEFREQ*            solvefreqdata;      /**< solve frequency data */
   SCIP_Real             priority;           /**< positive call priority to initialize bandit algorithms */
   int                   rootnodepriority;   /**< heuristic's priority for call at rootnode */
};
 
/** mutation neighborhood data structure */
struct data_mutation
{
   SCIP_RANDNUMGEN*      rng;                /**< random number generator */
};
 
/** crossover neighborhood data structure */
struct data_crossover
{
   int                   nsols;              /**< the number of solutions that crossover should combine */
   SCIP_RANDNUMGEN*      rng;                /**< random number generator to draw from the solution pool */
   SCIP_SOL*             selsol;             /**< best selected solution by crossover as reference point */
};
 
/** dins neighborhood data structure */
struct data_dins
{
   int                   npoolsols;          /**< number of pool solutions where binary solution values must agree */
};
 
struct data_trustregion
{
   SCIP_Real             violpenalty;        /**< the penalty for violating the trust region */
};
 
/** primal heuristic data */
struct SCIP_HeurData
{
   SCIP_BANDIT*          bandit;             /**< bandit algorithm */
   int*                  sortedindices;      /**< array of indices of heuristics sorted w.r.t. heuristic priorities */
   int                   counter;            /**< counter to count how often the scheduler selected a heuristic in the rootnode */
   SCIP_SOL*             lastcallsol;        /**< incumbent when the heuristic was last called */
   SCIP_Longint          waitingnodes;       /**< number of nodes since last incumbent solution that the heuristic should wait */
   SCIP_Longint          firstcallthissol;   /**< counter for the number of calls on this incumbent */
   char                  banditalgo;         /**< the bandit algorithm: (u)pper confidence bounds, (e)xp.3, epsilon (g)reedy */
   int                   maxcallssamesol;    /**< number of allowed executions of the heuristic on the same incumbent solution
                                              *   (-1: no limit, 0: number of active neighborhoods) */
   int                   nselections;        /**< number of heuristics picked by the scheduler in one call
                                              *   (-1: number of controlled heuristics, 0: until new incumbent is found) */
   int                   nskippedcalls;      /**< number of calls to heuristic we need to skip since last execution */
   int                   nfailedcalls;       /**< number of failed calls to heursitic since last successful one */
   SCIP_Bool             resetweights;       /**< should the bandit algorithms be reset when a new problem is read? */
   SCIP_Bool             initduringroot;     /**< should the heuristic be executed multiple times during the root node? */
   int                   maxnconflicts;      /**< maximum number of conflicts detected by diving heur so far */
   SCIP_Bool             defaultroot;        /**< should the default priorities be used at the root node */
   SCIP_Real             heurtimelimit;      /**< time limit for a single heuristic run */
   /* bandit algorithm parameters */
   SCIP_Real             exp3_gamma;         /**< weight between uniform (gamma ~ 1) and weight driven (gamma ~ 0) probability distribution for exp3 */
   SCIP_Real             exp3_beta;          /**< reward offset between 0 and 1 at every observation for exp3 */
   SCIP_Real             epsgreedy_eps;      /**< increase exploration in epsilon-greedy bandit algorithm */
   SCIP_Bool             epsgreedy_usemod;   /**< TRUE if modified version of the epsilon-greedy bandit algorithm should be used */
   SCIP_Real             ucb_alpha;          /**< parameter to increase the confidence width in UCB */
   /* reward function parameters (reward is a function between 0 and 1 and thus always upper bounded by 1, even if
    * sum of weights do not add up to 1.0) */
   SCIP_Real             solrewardweight;    /**< weight by how much finding a new incumbent is rewarded in reward function */
   SCIP_Real             effortrewardweight; /**< weight by how much effort is rewarded in reward function */
   SCIP_Real             qualrewardweight;   /**< weight by how much quality of a new incumbent is rewarded in reward function */
   SCIP_Real             conflictrewardweight;/**< weight by how much number of conflicts found by diving is rewarded in reward function */
   /* diving data */
   SCIP_SOL*             sol;                /**< working solution */
   DIVING_HEUR**         divingheurs;        /**< array of diving heuristics */
   int                   divingheurssize;    /**< array size for diving heurs array */
   int                   ndiving;            /**< number of diving heuristics used by scheduler */
   SCIP_Longint          initdivingnodelimit;/**< initial node limit for diving heuristics */
   SCIP_Longint          maxdivingnodelimit; /**< maximum of node limits among all diving heurisitics */
   /* LNS data */
   NH**                  neighborhoods;      /**< array of neighborhoods */
   SCIP_Longint          nodesoffset;        /**< offset added to the nodes budget */
   SCIP_Longint          maxnodes;           /**< maximum number of nodes in a single sub-SCIP */
   SCIP_Longint          targetnodes;        /**< targeted number of nodes to start a sub-SCIP */
   SCIP_Longint          minnodes;           /**< minimum number of nodes required to start a sub-SCIP */
   SCIP_Longint          usednodes;          /**< total number of nodes already spent in sub-SCIPs */
   SCIP_Real             nodesquot;          /**< fraction of nodes compared to the main SCIP for budget computation */
   SCIP_Real             nodesquotmin;       /**< lower bound on fraction of nodes compared to the main SCIP for budget computation */
   SCIP_Real             lplimfac;           /**< limit fraction of LPs per node to interrupt sub-SCIP */
   SCIP_Real             targetnodefactor;   /**< factor by which target node number is eventually increased */
   SCIP_Real             fixtol;             /**< tolerance by which the fixing rate may be missed without generic fixing */
   SCIP_Real             unfixtol;           /**< tolerance by which the fixing rate may be exceeded without generic unfixing */
   int                   nneighborhoods;     /**< number of neighborhoods */
   int                   nactiveneighborhoods;/**< number of active neighborhoods */
   int                   ninitneighborhoods; /**< neighborhoods that were used at least one time */
   int                   nsolslim;           /**< limit on the number of improving solutions in a sub-SCIP call */
   int                   seed;               /**< initial random seed for bandit algorithms and random decisions by neighborhoods */
   int                   currneighborhood;   /**< index of currently selected neighborhood */
   int                   ndelayedcalls;      /**< the number of delayed calls */
   SCIP_Bool             usesubscipheurs;    /**< should the heuristic activate other sub-SCIP heuristics during its search?  */
   SCIP_Bool             subsciprandseeds;   /**< should random seeds of sub-SCIPs be altered to increase diversification? */
   SCIP_Bool             copycuts;           /**< should cutting planes be copied to the sub-SCIP? */
   int                   initlnsnodelimit;   /**< initial node limit for LNS heuristics */
   int                   maxlnsnodelimit;    /**< maximum of nodelimits among all LNS heuristics */
   SCIP_Bool             useredcost;         /**< should reduced cost scores be used for variable prioritization? */
   SCIP_Bool             usedistances;       /**< should distances from fixed variables be used for variable prioritization */
   SCIP_Bool             usepscost;          /**< should pseudo cost scores be used for variable prioritization? */
   SCIP_Bool             uselocalredcost;    /**< should local reduced costs be used for generic (un)fixing? */
};
 
/** event handler data */
struct SCIP_EventData
{
   SCIP_VAR**            subvars;            /**< the variables of the subproblem */
   SCIP*                 sourcescip;         /**< original SCIP data structure */
   SCIP_HEUR*            heur;               /**< scheduler heuristic structure */
   SCIP_Longint          nodelimit;          /**< node limit of the run */
   SCIP_Real             lplimfac;           /**< limit fraction of LPs per node to interrupt sub-SCIP */
   HEUR_STATS*           runstats;           /**< run statistics for the current neighborhood */
};
 
/** represents limits for the sub-SCIP solving process */
struct SolveLimits
{
   SCIP_Longint          nodelimit;          /**< maximum number of solving nodes for the sub-SCIP */
   SCIP_Real             memorylimit;        /**< memory limit for the sub-SCIP */
   SCIP_Real             timelimit;          /**< time limit for the sub-SCIP */
   SCIP_Longint          stallnodes;         /**< maximum number of nodes without (primal) stalling */
};
 
typedef struct SolveLimits SOLVELIMITS;
 
/** data structure that can be used for variable prioritization for additional fixings */
struct VarPrio
{
   SCIP*                 scip;               /**< SCIP data structure */
   SCIP_Real*            randscores;         /**< random scores for prioritization */
   int*                  distances;          /**< breadth-first distances from already fixed variables */
   SCIP_Real*            redcostscores;      /**< reduced cost scores for fixing a variable to a reference value */
   SCIP_Real*            pscostscores;       /**< pseudocost scores for fixing a variable to a reference value */
   unsigned int          useredcost:1;       /**< should reduced cost scores be used for variable prioritization? */
   unsigned int          usedistances:1;     /**< should distances from fixed variables be used for variable prioritization */
   unsigned int          usepscost:1;        /**< should pseudo cost scores be used for variable prioritization? */
};
 
/*
 * Local methods
 */
 
/** Reset target fixing rate */
static
SCIP_RETCODE resetFixingRate(
   SCIP*                 scip,               /**< SCIP data structure */
   NH_FIXINGRATE*        fixingrate          /**< heuristic fixing rate */
   )
{
   assert(scip != NULL);
   assert(fixingrate != NULL);
   fixingrate->increment = FIXINGRATE_STARTINC;
 
   /* always start with the most conservative value */
   fixingrate->targetfixingrate = fixingrate->maxfixingrate;
 
   return SCIP_OKAY;
}
 
/** update increment for fixing rate */
static
void updateFixingRateIncrement(
   NH_FIXINGRATE*        fx                  /**< fixing rate */
   )
{
   fx->increment *= FIXINGRATE_DECAY;
   fx->increment = MAX(fx->increment, LRATEMIN);
}
 
/** increase fixing rate
 *
 *  decrease also the rate by which the target fixing rate is adjusted
 */
static
void increaseFixingRate(
   NH_FIXINGRATE*        fx                  /**< fixing rate */
   )
{
   fx->targetfixingrate += fx->increment;
   fx->targetfixingrate = MIN(fx->targetfixingrate, fx->maxfixingrate);
}
 
/** decrease fixing rate
 *
 *  decrease also the rate by which the target fixing rate is adjusted
 */
static
void decreaseFixingRate(
   NH_FIXINGRATE*        fx                  /**< fixing rate */
   )
{
   fx->targetfixingrate -= fx->increment;
   fx->targetfixingrate = MAX(fx->targetfixingrate, fx->minfixingrate);
}
 
/** update fixing rate based on the results of the current run */
static
void updateFixingRate(
   NH*                   neighborhood,       /**< neighborhood */
   SCIP_STATUS           subscipstatus,      /**< status of the sub-SCIP run */
   HEUR_STATS*           runstats            /**< run statistics for this run */
   )
{
   NH_FIXINGRATE* fx;
 
   fx = &neighborhood->fixingrate;
 
   switch (subscipstatus)
   {
   case SCIP_STATUS_OPTIMAL:
   case SCIP_STATUS_INFEASIBLE:
   case SCIP_STATUS_INFORUNBD:
   case SCIP_STATUS_SOLLIMIT:
   case SCIP_STATUS_BESTSOLLIMIT:
      /* decrease the fixing rate (make subproblem harder) */
      decreaseFixingRate(fx);
      break;
   case SCIP_STATUS_STALLNODELIMIT:
   case SCIP_STATUS_USERINTERRUPT:
   case SCIP_STATUS_TERMINATE:
   case SCIP_STATUS_TIMELIMIT:
   case SCIP_STATUS_NODELIMIT:
      /* increase the fixing rate (make the subproblem easier) only if no solution was found */
      if( runstats->nbestsolsfound <= 0 )
         increaseFixingRate(fx);
      break;
      /* fall through cases to please lint */
   case SCIP_STATUS_UNKNOWN:
   case SCIP_STATUS_TOTALNODELIMIT:
   case SCIP_STATUS_MEMLIMIT:
   case SCIP_STATUS_GAPLIMIT:
   case SCIP_STATUS_PRIMALLIMIT:
   case SCIP_STATUS_DUALLIMIT:
   case SCIP_STATUS_RESTARTLIMIT:
   case SCIP_STATUS_UNBOUNDED:
   default:
      break;
   }
 
   updateFixingRateIncrement(fx);
}
 
/** reset the currently active neighborhood */
static
void resetCurrentNeighborhood(
   SCIP_HEURDATA*        heurdata
   )
{
   assert(heurdata != NULL);
   heurdata->currneighborhood = -1;
   heurdata->ndelayedcalls = 0;
}
 
/** reset target node limit */
static
void resetTargetNodeLimit(
   SCIP_HEURDATA*        heurdata            /**< heuristic data */
   )
{
   heurdata->targetnodes = heurdata->minnodes;
}
 
/** Reset neighborhood statistics */
static
SCIP_RETCODE heurStatsReset(
   SCIP*                 scip,               /**< SCIP data structure */
   HEUR_STATS*           stats,              /**< heuristic statistics */
   SCIP_Bool             usediving           /**< TRUE if the statistics belong to a diving heuristic */
   )
{
   assert(scip != NULL);
   assert(stats != NULL);
 
   stats->nbestsolsfound = 0;
   stats->nruns = 0;
   stats->nrunsbestsol = 0;
   stats->nsolsfound = 0;
   stats->usednodes = 0L;
   stats->nfixings = 0L;
   stats->nbacktracks = 0L;
   stats->nconflicts = 0L;
   stats->nprobnodes = 0L;
   stats->divingdepth = 0;
 
   SCIP_CALL( SCIPresetClock(scip, stats->setupclock) );
   SCIP_CALL( SCIPresetClock(scip, stats->execclock) );
 
   /* if we use diving, these stats are not used (and memory not allocated) */
   if( ! usediving )
   {
      BMSclearMemoryArray(stats->statushist, NHISTENTRIES);
   }
 
   return SCIP_OKAY;
}
 
/** create a neighborhood of the specified name and include it into the scheduler heuristic */
static
SCIP_RETCODE schedulerIncludeNeighborhood(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data of the scheduler heuristic */
   NH**                  neighborhood,       /**< pointer to store the neighborhood */
   const char*           name,               /**< name for this neighborhood */
   SCIP_Real             minfixingrate,      /**< default value for minfixingrate parameter of this neighborhood */
   SCIP_Real             maxfixingrate,      /**< default value for maxfixingrate parameter of this neighborhood */
   SCIP_Bool             active,             /**< default value for active parameter of this neighborhood */
   int                   priority,           /**< priority for heuristic in rootnode */
   DECL_VARFIXINGS       ((*varfixings)),    /**< variable fixing callback for this neighborhood, or NULL */
   DECL_CHANGESUBSCIP    ((*changesubscip)), /**< subscip changes callback for this neighborhood, or NULL */
   DECL_NHINIT           ((*nhinit)),        /**< initialization callback for neighborhood, or NULL */
   DECL_NHEXIT           ((*nhexit)),        /**< deinitialization callback for neighborhood, or NULL */
   DECL_NHFREE           ((*nhfree)),        /**< deinitialization callback before SCIP is freed, or NULL */
   DECL_NHREFSOL         ((*nhrefsol)),      /**< callback function to return a reference solution for further fixings, or NULL */
   DECL_NHDEACTIVATE     ((*nhdeactivate))   /**< callback function to deactivate neighborhoods on problems where they are irrelevant, or NULL if neighborhood is always active */
   )
{
   char paramname[SCIP_MAXSTRLEN];
 
   assert(scip != NULL);
   assert(heurdata != NULL);
   assert(neighborhood != NULL);
   assert(name != NULL);
 
   SCIP_CALL( SCIPallocBlockMemory(scip, neighborhood) );
   assert(*neighborhood != NULL);
 
   SCIP_ALLOC( BMSduplicateMemoryArray(&(*neighborhood)->name, name, strlen(name)+1) );
 
   SCIP_CALL( SCIPcreateClock(scip, &(*neighborhood)->stats.setupclock) );
   SCIP_CALL( SCIPcreateClock(scip, &(*neighborhood)->stats.execclock) );
 
   (*neighborhood)->changesubscip = changesubscip;
   (*neighborhood)->varfixings = varfixings;
   (*neighborhood)->nhinit = nhinit;
   (*neighborhood)->nhexit = nhexit;
   (*neighborhood)->nhfree = nhfree;
   (*neighborhood)->nhrefsol = nhrefsol;
   (*neighborhood)->nhdeactivate = nhdeactivate;
 
   (*neighborhood)->rootnodepriority = priority;
 
   /* add parameters for this neighborhood */
   (void) SCIPsnprintf(paramname, SCIP_MAXSTRLEN, "heuristics/scheduler/%s/minfixingrate", name);
   SCIP_CALL( SCIPaddRealParam(scip, paramname, "minimum fixing rate for this neighborhood",
         &(*neighborhood)->fixingrate.minfixingrate, TRUE, minfixingrate, 0.0, 1.0, NULL, NULL) );
   (void) SCIPsnprintf(paramname, SCIP_MAXSTRLEN, "heuristics/scheduler/%s/maxfixingrate", name);
   SCIP_CALL( SCIPaddRealParam(scip, paramname, "maximum fixing rate for this neighborhood",
         &(*neighborhood)->fixingrate.maxfixingrate, TRUE, maxfixingrate, 0.0, 1.0, NULL, NULL) );
   (void) SCIPsnprintf(paramname, SCIP_MAXSTRLEN, "heuristics/scheduler/%s/active", name);
   SCIP_CALL( SCIPaddBoolParam(scip, paramname, "is this neighborhood active?",
         &(*neighborhood)->active, TRUE, active, NULL, NULL) );
   (void) SCIPsnprintf(paramname, SCIP_MAXSTRLEN, "heuristics/scheduler/%s/priority", name);
   SCIP_CALL( SCIPaddRealParam(scip, paramname, "positive call priority to initialize bandit algorithms",
         &(*neighborhood)->priority, TRUE, 1.0, 1e-2, 1.0, NULL, NULL) );
 
   /* add the neighborhood to heuristic */
   heurdata->neighborhoods[heurdata->nneighborhoods++] = (*neighborhood);
 
   return SCIP_OKAY;
}
 
/** release all data and free neighborhood */
static
SCIP_RETCODE schedulerFreeNeighborhood(
   SCIP*                 scip,               /**< SCIP data structure */
   NH**                  neighborhood        /**< pointer to neighborhood that should be freed */
   )
{
   NH* nhptr;
   assert(scip != NULL);
   assert(neighborhood != NULL);
 
   nhptr = *neighborhood;
   assert(nhptr != NULL);
 
   BMSfreeMemoryArray(&nhptr->name);
 
   /* release further, neighborhood specific data structures */
   if( nhptr->nhfree != NULL )
   {
      SCIP_CALL( nhptr->nhfree(scip, nhptr) );
   }
 
   SCIP_CALL( SCIPfreeClock(scip, &nhptr->stats.setupclock) );
   SCIP_CALL( SCIPfreeClock(scip, &nhptr->stats.execclock) );
 
   SCIPfreeBlockMemory(scip, neighborhood);
   *neighborhood = NULL;
 
   return SCIP_OKAY;
}
 
/** initialize neighborhood specific data */
static
SCIP_RETCODE neighborhoodInit(
   SCIP*                 scip,               /**< SCIP data structure */
   NH*                   neighborhood        /**< neighborhood to initialize */
   )
{
   assert(scip != NULL);
   assert(neighborhood != NULL);
 
   /* call the init callback of the neighborhood */
   if( neighborhood->nhinit != NULL )
   {
      SCIP_CALL( neighborhood->nhinit(scip, neighborhood) );
   }
 
   return SCIP_OKAY;
}
 
/** deinitialize neighborhood specific data */
static
SCIP_RETCODE neighborhoodExit(
   SCIP*                 scip,               /**< SCIP data structure */
   NH*                   neighborhood        /**< neighborhood to initialize */
   )
{
   assert(scip != NULL);
   assert(neighborhood != NULL);
 
   if( neighborhood->nhexit != NULL )
   {
      SCIP_CALL( neighborhood->nhexit(scip, neighborhood) );
   }
 
   return SCIP_OKAY;
}
 
/** creates a new solution for the original problem by copying the solution of the subproblem */
static
SCIP_RETCODE transferSolution(
   SCIP*                 subscip,            /**< SCIP data structure of the subproblem */
   SCIP_EVENTDATA*       eventdata           /**< event handler data */
   )
{
   SCIP*      sourcescip;         /* original SCIP data structure */
   SCIP_VAR** subvars;            /* the variables of the subproblem */
   SCIP_HEUR* heur;               /* scheduler heuristic structure */
   SCIP_SOL*  subsol;             /* solution of the subproblem */
   SCIP_SOL*  newsol;             /* solution to be created for the original problem */
   SCIP_Bool  success;
   HEUR_STATS*  runstats;
   SCIP_SOL*  oldbestsol;
 
   assert(subscip != NULL);
 
   subsol = SCIPgetBestSol(subscip);
   assert(subsol != NULL);
 
   sourcescip = eventdata->sourcescip;
   subvars = eventdata->subvars;
   heur = eventdata->heur;
   runstats = eventdata->runstats;
   assert(sourcescip != NULL);
   assert(sourcescip != subscip);
   assert(heur != NULL);
   assert(subvars != NULL);
   assert(runstats != NULL);
 
   SCIP_CALL( SCIPtranslateSubSol(sourcescip, subscip, subsol, heur, subvars, &newsol) );
 
   oldbestsol = SCIPgetBestSol(sourcescip);
 
   /* try to add new solution to scip and free it immediately */
   SCIP_CALL( SCIPtrySolFree(sourcescip, &newsol, FALSE, FALSE, TRUE, TRUE, TRUE, &success) );
 
   if( success )
   {
      runstats->nsolsfound++;
      if( SCIPgetBestSol(sourcescip) != oldbestsol )
         runstats->nbestsolsfound++;
   }
 
   /* update new upper bound for reward later */
   runstats->newupperbound = SCIPgetUpperbound(sourcescip);
 
   return SCIP_OKAY;
}
 
/** release all data and free diving heuristic */
static
SCIP_RETCODE schedulerFreeDivingHeur(
   SCIP*                 scip,               /**< SCIP data structure */
   DIVING_HEUR**         divingheur          /**< pointer to diving heuristic that should be freed */
   )
{
   DIVING_HEUR* divingheurptr;
   assert(scip != NULL);
   assert(divingheur != NULL);
 
   divingheurptr = *divingheur;
   assert(divingheurptr != NULL);
 
   SCIP_CALL( SCIPfreeClock(scip, &divingheurptr->stats->setupclock) );
   SCIP_CALL( SCIPfreeClock(scip, &divingheurptr->stats->execclock) );
 
   SCIPfreeBlockMemory(scip, &divingheurptr->solvefreqdata);
   SCIPfreeBlockMemory(scip, &divingheurptr->stats);
   SCIPfreeBlockMemory(scip, divingheur);
 
   return SCIP_OKAY;
}
 
/* ---------------- Callback methods of event handler ---------------- */
 
/** execution callback of the event handler
 *
 * transfer new solutions or interrupt the solving process manually
 */
static
SCIP_DECL_EVENTEXEC(eventExecScheduler)
{
   assert(eventhdlr != NULL);
   assert(eventdata != NULL);
   assert(strcmp(SCIPeventhdlrGetName(eventhdlr), EVENTHDLR_NAME) == 0);
   assert(event != NULL);
   assert(SCIPeventGetType(event) & SCIP_EVENTTYPE_SCHEDULER);
   assert(eventdata != NULL);
 
   /* treat the different atomic events */
   switch( SCIPeventGetType(event) )
   {
   case SCIP_EVENTTYPE_SOLFOUND:
   case SCIP_EVENTTYPE_BESTSOLFOUND:
      /* try to transfer the solution to the original SCIP */
      SCIP_CALL( transferSolution(scip, eventdata) );
      break;
   case SCIP_EVENTTYPE_LPSOLVED:
      /* interrupt solution process of sub-SCIP */
      if( SCIPgetNLPs(scip) > eventdata->lplimfac * eventdata->nodelimit )
      {
         SCIPdebugMsg(scip, "interrupt after  %" SCIP_LONGINT_FORMAT " LPs\n", SCIPgetNLPs(scip));
         SCIP_CALL( SCIPinterruptSolve(scip) );
      }
      break;
   default:
      break;
   }
 
   return SCIP_OKAY;
}
 
/** initialize heuristic statistics before the next run */
static
void initRunStats(
   SCIP*                 scip,               /**< SCIP data structure */
   HEUR_STATS*           stats               /**< run statistics */
   )
{
   stats->nbestsolsfound = 0;
   stats->nsolsfound = 0;
   stats->usednodes = 0L;
   stats->nprobnodes = 0L;
   stats->nbacktracks = 0L;
   stats->nconflicts = 0L;
   stats->nfixings = 0;
   stats->divingdepth = 0;
   stats->oldupperbound = SCIPgetUpperbound(scip);
   stats->newupperbound = SCIPgetUpperbound(scip);
}
 
/** update run stats after the sub SCIP was solved */
static
void updateRunStats(
   HEUR_STATS*           stats,              /**< run statistics */
   SCIP*                 subscip             /**< sub-SCIP instance, or NULL */
   )
{
   /* treat an untransformed subscip as if none was created */
   if( subscip != NULL && ! SCIPisTransformed(subscip) )
      subscip = NULL;
 
   stats->usednodes = subscip != NULL ? SCIPgetNNodes(subscip) : 0L;
}
 
/** get the histogram index for this status */
static
int getHistIndex(
   SCIP_STATUS           subscipstatus       /**< sub-SCIP status */
   )
{
   switch (subscipstatus)
   {
   case SCIP_STATUS_OPTIMAL:
      return (int)HIDX_OPT;
   case SCIP_STATUS_INFEASIBLE:
      return (int)HIDX_INFEAS;
   case SCIP_STATUS_NODELIMIT:
      return (int)HIDX_NODELIM;
   case SCIP_STATUS_STALLNODELIMIT:
      return (int)HIDX_STALLNODE;
   case SCIP_STATUS_SOLLIMIT:
   case SCIP_STATUS_BESTSOLLIMIT:
      return (int)HIDX_SOLLIM;
   case SCIP_STATUS_USERINTERRUPT:
      return (int)HIDX_USR;
   default:
      return (int)HIDX_OTHER;
   } /*lint !e788*/
}
 
/** print neighborhood statistics */
static
void printNeighborhoodStatistics(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data */
   FILE*                 file                /**< file handle, or NULL for standard out */
   )
{
   int i;
   int j;
   HISTINDEX statusses[] = {HIDX_OPT, HIDX_INFEAS, HIDX_NODELIM, HIDX_STALLNODE, HIDX_SOLLIM, HIDX_USR, HIDX_OTHER};
 
   SCIPinfoMessage(scip, file, "LNS (Scheduler)    : %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %4s %4s %4s %4s %4s %4s %4s %4s\n",
            "Calls", "SetupTime", "SolveTime", "SolveNodes", "Sols", "Best", "Exp3", "Exp3-IX", "EpsGreedy", "UCB", "TgtFixRate",
            "Opt", "Inf", "Node", "Stal", "Sol", "Usr", "Othr", "Actv");
 
   /* loop over neighborhoods and fill in statistics */
   for( i = 0; i < heurdata->nneighborhoods; ++i )
   {
      NH* neighborhood;
      SCIP_Real proba;
      SCIP_Real probaix;
      SCIP_Real ucb;
      SCIP_Real epsgreedyweight;
 
      neighborhood = heurdata->neighborhoods[i];
      SCIPinfoMessage(scip, file, "  %-17s:", neighborhood->name);
      SCIPinfoMessage(scip, file, " %10d", neighborhood->stats.nruns);
      SCIPinfoMessage(scip, file, " %10.2f", SCIPgetClockTime(scip, neighborhood->stats.setupclock) );
      SCIPinfoMessage(scip, file, " %10.2f", SCIPgetClockTime(scip, neighborhood->stats.execclock) );
      SCIPinfoMessage(scip, file, " %10" SCIP_LONGINT_FORMAT, neighborhood->stats.usednodes );
      SCIPinfoMessage(scip, file, " %10" SCIP_LONGINT_FORMAT, neighborhood->stats.nsolsfound);
      SCIPinfoMessage(scip, file, " %10" SCIP_LONGINT_FORMAT, neighborhood->stats.nbestsolsfound);
 
      proba = 0.0;
      probaix = 0.0;
      ucb = 1.0;
      epsgreedyweight = -1.0;
 
      if( heurdata->bandit != NULL && i < heurdata->nactiveneighborhoods )
      {
         switch (heurdata->banditalgo)
         {
         case 'u':
            ucb = SCIPgetConfidenceBoundUcb(heurdata->bandit, i + heurdata->ndiving ); /* note: we need to shift the index since LNS heuristics come after diving */
            break;
         case 'g':
            epsgreedyweight = SCIPgetWeightsEpsgreedy(heurdata->bandit)[i + heurdata->ndiving];
            break;
         case 'e':
            proba = SCIPgetProbabilityExp3(heurdata->bandit, i + heurdata->ndiving);
            break;
         case 'i':
            probaix = SCIPgetProbabilityExp3IX(heurdata->bandit, i + heurdata->ndiving);
            break;
         default:
            break;
         }
      }
 
      SCIPinfoMessage(scip, file, " %10.5f", proba);
      SCIPinfoMessage(scip, file, " %10.5f", probaix);
      SCIPinfoMessage(scip, file, " %10.5f", epsgreedyweight);
      SCIPinfoMessage(scip, file, " %10.5f", ucb);
      SCIPinfoMessage(scip, file, " %10.3f", neighborhood->fixingrate.targetfixingrate);
 
      /* loop over status histogram */
      for( j = 0; j < NHISTENTRIES; ++j )
         SCIPinfoMessage(scip, file, " %4d", neighborhood->stats.statushist[statusses[j]]);
 
      SCIPinfoMessage(scip, file, " %4d", i < heurdata->nactiveneighborhoods ? 1 : 0);
      SCIPinfoMessage(scip, file, "\n");
   }
}
 
/** print diving heuristic statistics */
static
void printDivingHeurStatistics(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data */
   FILE*                 file                /**< file handle, or NULL for standard out */
   )
{
   int i;
 
   SCIPinfoMessage(scip, file, "Diving (Scheduler) : %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s \n",
            "Calls", "SetupTime", "SolveTime", "SolveNodes", "Sols", "Best", "Exp3", "Exp3-IX", "EpsGreedy", "UCB", "LPResolveQuot", "MaxDiveDepth");
 
   /* loop over neighborhoods and fill in statistics */
   for( i = 0; i < heurdata->ndiving; ++i )
   {
      DIVING_HEUR* divingheur;
      SCIP_Real proba;
      SCIP_Real probaix;
      SCIP_Real ucb;
      SCIP_Real epsgreedyweight;
 
      divingheur = heurdata->divingheurs[i];
      SCIPinfoMessage(scip, file, "  %-17s:", SCIPdivesetGetName(divingheur->diveset));
      SCIPinfoMessage(scip, file, " %10d", divingheur->stats->nruns);
      SCIPinfoMessage(scip, file, " %10.2f", SCIPgetClockTime(scip, divingheur->stats->setupclock) );
      SCIPinfoMessage(scip, file, " %10.2f", SCIPgetClockTime(scip, divingheur->stats->execclock) );
      SCIPinfoMessage(scip, file, " %10" SCIP_LONGINT_FORMAT, divingheur->stats->nprobnodes );
      SCIPinfoMessage(scip, file, " %10" SCIP_LONGINT_FORMAT, divingheur->stats->nsolsfound);
      SCIPinfoMessage(scip, file, " %10" SCIP_LONGINT_FORMAT, divingheur->stats->nbestsolsfound);
 
      proba = 0.0;
      probaix = 0.0;
      ucb = 1.0;
      epsgreedyweight = -1.0;
 
      if( heurdata->bandit != NULL )
      {
         switch (heurdata->banditalgo)
         {
         case 'u':
            ucb = SCIPgetConfidenceBoundUcb(heurdata->bandit, i);
            break;
         case 'g':
            epsgreedyweight = SCIPgetWeightsEpsgreedy(heurdata->bandit)[i];
            break;
         case 'e':
            proba = SCIPgetProbabilityExp3(heurdata->bandit, i);
            break;
         case 'i':
            probaix = SCIPgetProbabilityExp3IX(heurdata->bandit, i);
            break;
         default:
            break;
         }
      }
 
      SCIPinfoMessage(scip, file, " %10.5f", proba);
      SCIPinfoMessage(scip, file, " %10.5f", probaix);
      SCIPinfoMessage(scip, file, " %10.5f", epsgreedyweight);
      SCIPinfoMessage(scip, file, " %10.5f", ucb);
      SCIPinfoMessage(scip, file, " %10.3f", divingheur->solvefreqdata->currentsolvefreq);
      SCIPinfoMessage(scip, file, " %10lld", divingheur->nodelimit);
 
      SCIPinfoMessage(scip, file, "\n");
   }
}
 
/** update the statistics of the diving heuristic based on the heuristic run */
static
void updateHeurStatsDiving(
   HEUR_STATS*           runstats,           /**< run statistics */
   DIVING_HEUR*          divingheur          /**< the selected diving heuristic or NULL if LNS was used */
   )
{  /*lint --e{715}*/
   HEUR_STATS* stats;
 
   assert(divingheur != NULL);
 
   stats = divingheur->stats;
 
   /* update diving specific statistics */
   stats->nprobnodes += runstats->nprobnodes;
   stats->nbacktracks += runstats->nbacktracks;
   stats->nconflicts += runstats->nconflicts;
 
   /* copy run statistics into heur statistics */
   stats->nbestsolsfound += runstats->nbestsolsfound;
   stats->nsolsfound += runstats->nsolsfound;
   stats->nruns += 1;
 
   if( runstats->nbestsolsfound > 0 )
      stats->nrunsbestsol += DEFAULT_BESTSOLWEIGHT;
   else if( runstats->nsolsfound > 0 )
      stats->nrunsbestsol++;
}
 
/** update the statistics of LNS heuristic based on the heuristic run */
static
void updateHeurStatsLNS(
   HEUR_STATS*           runstats,           /**< run statistics */
   NH*                   neighborhood,       /**< the selected neighborhood or NULL if diving was used */
   SCIP_STATUS*          subscipstatus       /**< status of the sub-SCIP solve or NULL if diving was used */
   )
{  /*lint --e{715}*/
   HEUR_STATS* stats;
 
   assert( subscipstatus != NULL );
 
   stats = &neighborhood->stats;
 
   /* update LNS specific statistics */
   stats->usednodes += runstats->usednodes;
   ++stats->statushist[getHistIndex(*subscipstatus)]; /* update the counter for the subscip status */
 
   /* copy run statistics into heur statistics */
   stats->nbestsolsfound += runstats->nbestsolsfound;
   stats->nsolsfound += runstats->nsolsfound;
   stats->nruns += 1;
 
   if( runstats->nbestsolsfound > 0 )
      stats->nrunsbestsol += DEFAULT_BESTSOLWEIGHT;
   else if( runstats->nsolsfound > 0 )
      stats->nrunsbestsol++;
}
 
/** sort callback for variable pointers using the ALNS variable prioritization
 *
 *  the variable prioritization works hierarchically as follows. A variable
 *  a has the higher priority over b iff
 *
 *  - variable distances should be used and a has a smaller distance than b
 *  - variable reduced costs should be used and a has a smaller score than b
 *  - variable pseudo costs should be used and a has a smaller score than b
 *  - based on previously assigned random scores
 *
 *  @note: distances are context-based. For fixing more variables,
 *  distances are initialized from the already fixed variables.
 *  For unfixing variables, distances are initialized starting
 *  from the unfixed variables
 */
static
SCIP_DECL_SORTINDCOMP(sortIndCompScheduler)
{  /*lint --e{715}*/
   VARPRIO* varprio;
 
   varprio = (VARPRIO*)dataptr;
   assert(varprio != NULL);
   assert(varprio->randscores != NULL);
 
   if( ind1 == ind2 )
      return 0;
 
   /* priority is on distances, if enabled. The variable which is closer in a breadth-first search sense to
    * the already fixed variables has precedence */
   if( varprio->usedistances )
   {
      int dist1;
      int dist2;
 
      dist1 = varprio->distances[ind1];
      dist2 = varprio->distances[ind2];
 
      if( dist1 < 0 )
         dist1 = INT_MAX;
 
      if( dist2 < 0 )
         dist2 = INT_MAX;
 
      assert(varprio->distances != NULL);
      if( dist1 < dist2 )
         return -1;
      else if( dist1 > dist2 )
         return 1;
   }
 
   assert(! varprio->usedistances || varprio->distances[ind1] == varprio->distances[ind2]);
 
   /* if the indices tie considering distances or distances are disabled -> use reduced cost information instead */
   if( varprio->useredcost )
   {
      assert(varprio->redcostscores != NULL);
 
      if( varprio->redcostscores[ind1] < varprio->redcostscores[ind2] )
         return -1;
      else if( varprio->redcostscores[ind1] > varprio->redcostscores[ind2] )
         return 1;
   }
 
   /* use pseudo cost scores if reduced costs are disabled or a tie was found */
   if( varprio->usepscost )
   {
      assert(varprio->pscostscores != NULL);
 
      /* prefer the variable with smaller pseudocost score */
      if( varprio->pscostscores[ind1] < varprio->pscostscores[ind2] )
         return -1;
      else if( varprio->pscostscores[ind1] > varprio->pscostscores[ind2] )
         return 1;
   }
 
   if( varprio->randscores[ind1] < varprio->randscores[ind2] )
      return -1;
   else if( varprio->randscores[ind1] > varprio->randscores[ind2] )
      return 1;
 
   return ind1 - ind2;
}
 
/** Compute the reduced cost score for this variable in the reference solution */
static
SCIP_Real getVariableRedcostScore(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_VAR*             var,                /**< the variable for which the score should be computed */
   SCIP_Real             refsolval,          /**< solution value in reference solution */
   SCIP_Bool             uselocalredcost     /**< should local reduced costs be used for generic (un)fixing? */
   )
{
   SCIP_Real bestbound;
   SCIP_Real redcost;
   SCIP_Real score;
   assert(scip != NULL);
   assert(var != NULL);
 
   /* prefer column variables */
   if( SCIPvarGetStatus(var) != SCIP_VARSTATUS_COLUMN )
      return SCIPinfinity(scip);
 
   if( ! uselocalredcost )
   {
      redcost = SCIPvarGetBestRootRedcost(var);
 
      bestbound = SCIPvarGetBestRootSol(var);
 
      /* using global reduced costs, the two factors yield a nonnegative score within tolerances */
      assert(SCIPisDualfeasZero(scip, redcost)
         || (SCIPisDualfeasNegative(scip, redcost) && ! SCIPisFeasPositive(scip, refsolval - bestbound))
         || (SCIPisDualfeasPositive(scip, redcost) && ! SCIPisFeasNegative(scip, refsolval - bestbound)));
   }
   else
   {
      /* this can be safely asserted here, since the heuristic would not reach this point, otherwise */
      assert(SCIPhasCurrentNodeLP(scip));
      assert(SCIPgetLPSolstat(scip) == SCIP_LPSOLSTAT_OPTIMAL);
 
      redcost = SCIPgetVarRedcost(scip, var);
 
      bestbound = SCIPvarGetLPSol(var);
   }
 
   assert(! SCIPisInfinity(scip, REALABS(bestbound)));
   assert(SCIPisDualfeasZero(scip, redcost) || SCIPisFeasIntegral(scip, bestbound));
 
   score = redcost * (refsolval - bestbound);
 
   /* max out numerical inaccuracies from global scores */
   if( ! uselocalredcost )
      score = MAX(score, 0.0);
 
   return score;
}
 
/** get the pseudo cost score of this variable with respect to the reference solution */
static
SCIP_Real getVariablePscostScore(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_VAR*             var,                /**< the variable for which the score should be computed */
   SCIP_Real             refsolval,          /**< solution value in reference solution */
   SCIP_Bool             uselocallpsol       /**< should local LP solution be used? */
   )
{
   SCIP_Real lpsolval;
 
   assert(scip != NULL);
   assert(var != NULL);
 
   /* variables that aren't LP columns have no pseudocost score */
   if( SCIPvarGetStatus(var) != SCIP_VARSTATUS_COLUMN )
      return 0.0;
 
   lpsolval = uselocallpsol ? SCIPvarGetLPSol(var) : SCIPvarGetRootSol(var);
 
   /* the score is 0.0 if the values are equal */
   if( SCIPisEQ(scip, lpsolval, refsolval) )
      return 0.0;
   else
      return SCIPgetVarPseudocostVal(scip, var, refsolval - lpsolval);
}
 
/** add variable and solution value to buffer data structure for variable fixings. The method checks if
 *  the value still lies within the variable bounds. The value stays unfixed otherwise.
 */
static
void tryAdd2variableBuffer(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_VAR*             var,                /**< (source) SCIP variable that should be added to the buffer */
   SCIP_Real             val,                /**< fixing value for this variable */
   SCIP_VAR**            varbuf,             /**< variable buffer to store variables that should be fixed */
   SCIP_Real*            valbuf,             /**< value buffer to store fixing values */
   int*                  nfixings,           /**< pointer to number of fixed buffer variables, will be increased by 1 */
   SCIP_Bool             integer             /**< is this an integer variable? */
   )
{
   assert(SCIPisFeasIntegral(scip, val) || ! SCIPvarIsIntegral(var));
   assert(*nfixings < SCIPgetNVars(scip));
 
   /* round the value to its nearest integer */
   if( integer )
      val = SCIPfloor(scip, val + 0.5);
 
   /* only add fixing if it is still valid within the global variable bounds. Invalidity
    * of this solution value may come from a dual reduction that was performed after the solution from which
    * this value originated was found
    */
   if( SCIPvarGetLbGlobal(var) <= val && val <= SCIPvarGetUbGlobal(var) )
   {
      varbuf[*nfixings] = var;
      valbuf[*nfixings] = val;
      ++(*nfixings);
   }
}
 
/** fix additional variables found in feasible reference solution if the ones that the neighborhood found were not enough
 *
 *  use not always the best solution for the values, but a reference solution provided by the neighborhood itself
 *
 *  @note it may happen that the target fixing rate is not completely reached. This is the case if intermediate,
 *  dual reductions render the solution values of the reference solution infeasible for
 *  the current, global variable bounds.
 */
static
SCIP_RETCODE LNSFixMoreVariables(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data of the Scheduler neighborhood */
   SCIP_SOL*             refsol,             /**< feasible reference solution for more variable fixings */
   SCIP_VAR**            varbuf,             /**< buffer array to store variables to fix */
   SCIP_Real*            valbuf,             /**< buffer array to store fixing values */
   int*                  nfixings,           /**< pointer to store the number of fixings */
   int                   ntargetfixings,     /**< number of required target fixings */
   SCIP_Bool*            success             /**< pointer to store whether the target fixings have been successfully reached */
   )
{
   VARPRIO varprio;
   SCIP_VAR** vars;
   SCIP_Real* redcostscores;
   SCIP_Real* pscostscores;
   SCIP_Real* solvals;
   SCIP_RANDNUMGEN* rng;
   SCIP_VAR** unfixedvars;
   SCIP_Bool* isfixed;
   int* distances;
   int* perm;
   SCIP_Real* randscores;
   int nbinvars;
   int nintvars;
   int nbinintvars;
   int nvars;
   int b;
   int nvarstoadd;
   int nunfixedvars;
 
   assert(scip != NULL);
   assert(varbuf != NULL);
   assert(nfixings != NULL);
   assert(success != NULL);
   assert(heurdata != NULL);
   assert(refsol != NULL);
 
   *success = FALSE;
 
   SCIP_CALL( SCIPgetVarsData(scip, &vars, &nvars, &nbinvars, &nintvars, NULL, NULL) );
 
   nbinintvars = nbinvars + nintvars;
 
   if( ntargetfixings >= nbinintvars )
      return SCIP_OKAY;
 
   /* determine the number of required additional fixings */
   nvarstoadd = ntargetfixings - *nfixings;
   if( nvarstoadd == 0 )
      return SCIP_OKAY;
 
   varprio.usedistances = heurdata->usedistances && (*nfixings >= 1);
   varprio.useredcost = heurdata->useredcost;
   varprio.usepscost = heurdata->usepscost;
   varprio.scip = scip;
   rng = SCIPbanditGetRandnumgen(heurdata->bandit);
   assert(rng != NULL);
 
   SCIP_CALL( SCIPallocBufferArray(scip, &randscores, nbinintvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &perm, nbinintvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &distances, nvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &redcostscores, nbinintvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &solvals, nbinintvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &isfixed, nbinintvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &unfixedvars, nbinintvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &pscostscores, nbinintvars) );
 
   /* initialize variable graph distances from already fixed variables */
   if( varprio.usedistances )
   {
      SCIP_CALL( SCIPvariablegraphBreadthFirst(scip, NULL, varbuf, *nfixings, distances, INT_MAX, INT_MAX, ntargetfixings) );
   }
   else
   {
      /* initialize all equal distances to make them irrelevant */
      BMSclearMemoryArray(distances, nbinintvars);
   }
 
   BMSclearMemoryArray(isfixed, nbinintvars);
 
   /* mark binary and integer variables if they are fixed */
   for( b = 0; b < *nfixings; ++b )
   {
      int probindex;
 
      assert(varbuf[b] != NULL);
      probindex = SCIPvarGetProbindex(varbuf[b]);
      assert(probindex >= 0);
 
      if( probindex < nbinintvars )
         isfixed[probindex] = TRUE;
   }
 
   SCIP_CALL( SCIPgetSolVals(scip, refsol, nbinintvars, vars, solvals) );
 
   /* assign scores to unfixed every discrete variable of the problem */
   nunfixedvars = 0;
   for( b = 0; b < nbinintvars; ++b )
   {
      SCIP_VAR* var = vars[b];
 
      /* filter fixed variables */
      if( isfixed[b] )
         continue;
 
      /* filter variables with a solution value outside its global bounds */
      if( solvals[b] < SCIPvarGetLbGlobal(var) - 0.5 || solvals[b] > SCIPvarGetUbGlobal(var) + 0.5 )
         continue;
 
      redcostscores[nunfixedvars] = getVariableRedcostScore(scip, var, solvals[b], heurdata->uselocalredcost);
      pscostscores[nunfixedvars] = getVariablePscostScore(scip, var, solvals[b], heurdata->uselocalredcost);
 
      unfixedvars[nunfixedvars] = var;
      perm[nunfixedvars] = nunfixedvars;
      randscores[nunfixedvars] = SCIPrandomGetReal(rng, 0.0, 1.0);
 
      /* these assignments are based on the fact that nunfixedvars <= b */
      solvals[nunfixedvars] = solvals[b];
      distances[nunfixedvars] = distances[b];
 
      //SCIPdebugMsg(scip, "Var <%s> scores: dist %3d, red cost %15.9g, pscost %15.9g rand %6.4f\n",
      //   SCIPvarGetName(var), distances[nunfixedvars], redcostscores[nunfixedvars],
      //   pscostscores[nunfixedvars], randscores[nunfixedvars]);
 
      nunfixedvars++;
   }
 
   /* use selection algorithm (order of the variables does not matter) for quickly completing the fixing */
   varprio.randscores = randscores;
   varprio.distances = distances;
   varprio.redcostscores = redcostscores;
   varprio.pscostscores = pscostscores;
 
   nvarstoadd = MIN(nunfixedvars, nvarstoadd);
 
   /* select the first nvarstoadd many variables according to the score */
   if( nvarstoadd < nunfixedvars )
      SCIPselectInd(perm, sortIndCompScheduler, &varprio, nvarstoadd, nunfixedvars);
 
   /* loop over the first elements of the selection defined in permutation. They represent the best variables */
   for( b = 0; b < nvarstoadd; ++b )
   {
      int permindex = perm[b];
      assert(permindex >= 0);
      assert(permindex < nunfixedvars);
 
      tryAdd2variableBuffer(scip, unfixedvars[permindex], solvals[permindex], varbuf, valbuf, nfixings, TRUE);
   }
 
   *success = TRUE;
 
   /* free buffer arrays */
   SCIPfreeBufferArray(scip, &pscostscores);
   SCIPfreeBufferArray(scip, &unfixedvars);
   SCIPfreeBufferArray(scip, &isfixed);
   SCIPfreeBufferArray(scip, &solvals);
   SCIPfreeBufferArray(scip, &redcostscores);
   SCIPfreeBufferArray(scip, &distances);
   SCIPfreeBufferArray(scip, &perm);
   SCIPfreeBufferArray(scip, &randscores);
 
   return SCIP_OKAY;
}
 
/** create the bandit algorithm for the heuristic depending on the user parameter */
static
SCIP_RETCODE createBandit(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data structure */
   SCIP_Real*            priorities,         /**< call priorities for active neighborhoods */
   unsigned int          initseed            /**< initial random seed */
   )
{
   int nactions;
 
   nactions = heurdata->nactiveneighborhoods + heurdata->ndiving;
 
   switch (heurdata->banditalgo)
   {
   case 'u':
      SCIP_CALL( SCIPcreateBanditUcb(scip, &heurdata->bandit, priorities,
            heurdata->ucb_alpha, nactions, initseed) );
      break;
 
   case 'e':
      SCIP_CALL( SCIPcreateBanditExp3(scip, &heurdata->bandit, priorities,
            heurdata->exp3_gamma, heurdata->exp3_beta, nactions, initseed) );
      break;
 
   case 'i':
      SCIP_CALL( SCIPcreateBanditExp3IX(scip, &heurdata->bandit, priorities, nactions, initseed) );
      break;
 
   case 'g':
      SCIP_CALL( SCIPcreateBanditEpsgreedy(scip, &heurdata->bandit, priorities,
            heurdata->epsgreedy_eps, heurdata->epsgreedy_usemod, FALSE, 0.9, 0, nactions, initseed) );
      break;
 
   default:
      SCIPerrorMessage("Unknown bandit parameter %c\n", heurdata->banditalgo);
      return SCIP_INVALIDDATA;
   }
 
   return SCIP_OKAY;
}
 
/*
 * Callback methods of primal heuristic
 */
 
/** copy method for primal heuristic plugins (called when SCIP copies plugins) */
static
SCIP_DECL_HEURCOPY(heurCopyScheduler)
{  /*lint --e{715}*/
   assert(scip != NULL);
   assert(heur != NULL);
   assert(strcmp(SCIPheurGetName(heur), HEUR_NAME) == 0);
 
   /* call inclusion method of primal heuristic */
   SCIP_CALL( SCIPincludeHeurScheduler(scip) );
 
   return SCIP_OKAY;
}
 
/** query neighborhood for a reference solution for further fixings */
static
SCIP_RETCODE neighborhoodGetRefsol(
   SCIP*                 scip,               /**< SCIP data structure */
   NH*                   neighborhood,       /**< neighborhood data structure */
   SCIP_SOL**            solptr              /**< solution pointer */
   )
{
   assert(solptr != NULL);
   assert(scip != NULL);
   assert(neighborhood != NULL);
 
   *solptr = NULL;
   if( neighborhood->nhrefsol != NULL )
   {
      SCIP_RESULT result;
      SCIP_CALL( neighborhood->nhrefsol(scip, neighborhood, solptr, &result) );
 
      if( result == SCIP_DIDNOTFIND )
         *solptr = NULL;
      else
         assert(*solptr != NULL);
   }
 
   return SCIP_OKAY;
}
 
/** unfix some of the variables because there are too many fixed
 *
 *  a variable is ideally unfixed if it is close to other unfixed variables
 *  and fixing it has a high reduced cost impact
 */
static
SCIP_RETCODE LNSUnfixVariables(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data of neighborhood */
   SCIP_VAR**            varbuf,             /**< buffer array to store variables to fix */
   SCIP_Real*            valbuf,             /**< buffer array to store fixing values */
   int*                  nfixings,           /**< pointer to store the number of fixings */
   int                   ntargetfixings,     /**< number of required target fixings */
   SCIP_Bool*            success             /**< pointer to store whether the target fixings have been successfully reached */
   )
{
   VARPRIO varprio;
   SCIP_Real* redcostscores;
   SCIP_Real* pscostscores;
   SCIP_Real* randscores;
   SCIP_VAR** unfixedvars;
   SCIP_VAR** varbufcpy;
   SCIP_Real* valbufcpy;
   SCIP_Bool* isfixedvar;
   SCIP_VAR** vars;
   SCIP_RANDNUMGEN* rng;
   int* distances;
   int* fixeddistances;
   int* perm;
   int nvars;
   int i;
   int nbinintvars;
   int nunfixed;
 
   *success = FALSE;
 
   nbinintvars = SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip);
   if( nbinintvars == 0 )
      return SCIP_OKAY;
 
   assert(*nfixings > 0);
 
   nvars = SCIPgetNVars(scip);
   SCIP_CALL( SCIPallocBufferArray(scip, &isfixedvar, nvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &unfixedvars, nbinintvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &distances, nvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &fixeddistances, *nfixings) );
   SCIP_CALL( SCIPallocBufferArray(scip, &redcostscores, *nfixings) );
   SCIP_CALL( SCIPallocBufferArray(scip, &randscores, *nfixings) );
   SCIP_CALL( SCIPallocBufferArray(scip, &perm, *nfixings) );
   SCIP_CALL( SCIPallocBufferArray(scip, &pscostscores, *nfixings) );
 
   SCIP_CALL( SCIPduplicateBufferArray(scip, &varbufcpy, varbuf, *nfixings) );
   SCIP_CALL( SCIPduplicateBufferArray(scip, &valbufcpy, valbuf, *nfixings) );
 
   /*
    * collect the unfixed binary and integer variables
    */
   BMSclearMemoryArray(isfixedvar, nvars);
   /* loop over fixed variables and mark their respective positions as fixed */
   for( i = 0; i < *nfixings; ++i )
   {
      int probindex = SCIPvarGetProbindex(varbuf[i]);
 
      assert(probindex >= 0);
 
      isfixedvar[probindex] = TRUE;
   }
 
   nunfixed = 0;
   vars = SCIPgetVars(scip);
   /* collect unfixed binary and integer variables */
   for( i = 0; i < nbinintvars; ++i )
   {
      if( ! isfixedvar[i] )
         unfixedvars[nunfixed++] = vars[i];
   }
 
   varprio.usedistances = heurdata->usedistances && nunfixed > 0;
 
   /* collect distances of all fixed variables from those that are not fixed */
   if( varprio.usedistances )
   {
      SCIP_CALL( SCIPvariablegraphBreadthFirst(scip, NULL, unfixedvars, nunfixed, distances, INT_MAX, INT_MAX, INT_MAX) );
 
      for( i = 0; i < *nfixings; ++i )
      {
         int probindex = SCIPvarGetProbindex(varbuf[i]);
         if( probindex >= 0 )
            fixeddistances[i] = distances[probindex];
      }
   }
   else
   {
      BMSclearMemoryArray(fixeddistances, *nfixings);
   }
 
   /* collect reduced cost scores of the fixings and assign random scores */
   rng = SCIPbanditGetRandnumgen(heurdata->bandit);
   for( i = 0; i < *nfixings; ++i )
   {
      SCIP_VAR* fixedvar = varbuf[i];
      SCIP_Real fixval = valbuf[i];
 
      /* use negative reduced cost and pseudo cost scores to prefer variable fixings with small score */
      redcostscores[i] = - getVariableRedcostScore(scip, fixedvar, fixval, heurdata->uselocalredcost);
      pscostscores[i] = - getVariablePscostScore(scip, fixedvar, fixval, heurdata->uselocalredcost);
      randscores[i] = SCIPrandomGetReal(rng, 0.0, 1.0);
      perm[i] = i;
 
      //SCIPdebugMsg(scip, "Var <%s> scores: dist %3d, red cost %15.9g, pscost %15.9g rand %6.4f\n",
      //      SCIPvarGetName(fixedvar), fixeddistances[i], redcostscores[i], pscostscores[i], randscores[i]);
   }
 
   varprio.distances = fixeddistances;
   varprio.randscores = randscores;
   varprio.redcostscores = redcostscores;
   varprio.pscostscores = pscostscores;
   varprio.useredcost = heurdata->useredcost;
   varprio.usepscost = heurdata->usepscost;
   varprio.scip = scip;
 
   /* scores are assigned in such a way that variables with a smaller score should be fixed last */
   SCIPselectDownInd(perm, sortIndCompScheduler, &varprio, ntargetfixings, *nfixings);
 
   /* bring the desired variables to the front of the array */
   for( i = 0; i < ntargetfixings; ++i )
   {
      valbuf[i] = valbufcpy[perm[i]];
      varbuf[i] = varbufcpy[perm[i]];
   }
 
   *nfixings = ntargetfixings;
 
   /* free the buffer arrays in reverse order of allocation */
   SCIPfreeBufferArray(scip, &valbufcpy);
   SCIPfreeBufferArray(scip, &varbufcpy);
   SCIPfreeBufferArray(scip, &pscostscores);
   SCIPfreeBufferArray(scip, &perm);
   SCIPfreeBufferArray(scip, &randscores);
   SCIPfreeBufferArray(scip, &redcostscores);
   SCIPfreeBufferArray(scip, &fixeddistances);
   SCIPfreeBufferArray(scip, &distances);
   SCIPfreeBufferArray(scip, &unfixedvars);
   SCIPfreeBufferArray(scip, &isfixedvar);
 
   *success = TRUE;
 
   return SCIP_OKAY;
}
 
/** call variable fixing callback for this neighborhood and orchestrate additional variable fixings, if necessary */
static
SCIP_RETCODE neighborhoodFixVariables(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data of the scheduler neighborhood */
   NH*                   neighborhood,       /**< neighborhood data structure */
   SCIP_VAR**            varbuf,             /**< buffer array to keep variables that should be fixed */
   SCIP_Real*            valbuf,             /**< buffer array to keep fixing values */
   int*                  nfixings,           /**< pointer to store the number of variable fixings */
   SCIP_RESULT*          result              /**< pointer to store the result of the fixing operation */
   )
{
   int ntargetfixings;
   int nmaxfixings;
   int nminfixings;
   int nbinintvars;
 
   assert(scip != NULL);
   assert(neighborhood != NULL);
   assert(varbuf != NULL);
   assert(valbuf != NULL);
   assert(nfixings != NULL);
   assert(result != NULL);
 
   *nfixings = 0;
 
   *result = SCIP_DIDNOTRUN;
   ntargetfixings = (int)(neighborhood->fixingrate.targetfixingrate * (SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip)));
 
   if( neighborhood->varfixings != NULL )
   {
      SCIP_CALL( neighborhood->varfixings(scip, neighborhood, varbuf, valbuf, nfixings, result) );
 
      if( *result != SCIP_SUCCESS )
         return SCIP_OKAY;
   }
   else if( ntargetfixings == 0 )
   {
      *result = SCIP_SUCCESS;
      return SCIP_OKAY;
   }
 
      /* compute upper and lower target fixing limits using tolerance parameters */
   assert(neighborhood->varfixings == NULL || *result != SCIP_DIDNOTRUN);
   nbinintvars = SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip);
   ntargetfixings = (int)(neighborhood->fixingrate.targetfixingrate * nbinintvars);
   nminfixings = (int)((neighborhood->fixingrate.targetfixingrate - heurdata->fixtol) * nbinintvars);
   nminfixings = MAX(nminfixings, 0);
   nmaxfixings = (int)((neighborhood->fixingrate.targetfixingrate + heurdata->unfixtol) * nbinintvars);
   nmaxfixings = MIN(nmaxfixings, nbinintvars);
 
   SCIPdebugMsg(scip, "Neighborhood Fixings/Target: %d / %d <= %d <= %d\n",*nfixings, nminfixings, ntargetfixings, nmaxfixings);
 
   /* if too few fixings, use a strategy to select more variable fixings: randomized, LP graph, ReducedCost based, mix */
   if( (*result == SCIP_SUCCESS || *result == SCIP_DIDNOTRUN) && (*nfixings < nminfixings) )
   {
      SCIP_Bool success;
      SCIP_SOL* refsol;
 
      /* get reference solution from neighborhood */
      SCIP_CALL( neighborhoodGetRefsol(scip, neighborhood, &refsol) );
 
      /* try to fix more variables based on the reference solution */
      if( refsol != NULL )
      {
         SCIP_CALL( LNSFixMoreVariables(scip, heurdata, refsol, varbuf, valbuf, nfixings, ntargetfixings, &success) );
      }
      else
         success = FALSE;
 
      if( success )
         *result = SCIP_SUCCESS;
      else if( *result == SCIP_SUCCESS )
         *result = SCIP_DIDNOTFIND;
      else
         *result = SCIP_DIDNOTRUN;
 
      SCIPdebugMsg(scip, "After additional fixings: %d / %d\n",*nfixings, ntargetfixings);
   }
   else if( (SCIP_Real)(*nfixings) > nmaxfixings )
   {
      SCIP_Bool success;
 
      SCIP_CALL( LNSUnfixVariables(scip, heurdata, varbuf, valbuf, nfixings, ntargetfixings, &success) );
 
      assert(success);
      *result = SCIP_SUCCESS;
      SCIPdebugMsg(scip, "Unfixed variables, fixed variables remaining: %d\n", ntargetfixings);
   }
   else
   {
      SCIPdebugMsg(scip, "No additional fixings performed\n");
   }
 
   return SCIP_OKAY;
}
 
/** change the sub-SCIP by restricting variable domains, changing objective coefficients, or adding constraints */
static
SCIP_RETCODE neighborhoodChangeSubscip(
   SCIP*                 sourcescip,         /**< source SCIP data structure */
   SCIP*                 targetscip,         /**< target SCIP data structure */
   NH*                   neighborhood,       /**< neighborhood */
   SCIP_VAR**            targetvars,         /**< array of target SCIP variables aligned with source SCIP variables */
   int*                  ndomchgs,           /**< pointer to store the number of variable domain changes */
   int*                  nchgobjs,           /**< pointer to store the number of changed objective coefficients */
   int*                  naddedconss,        /**< pointer to store the number of added constraints */
   SCIP_Bool*            success             /**< pointer to store whether the sub-SCIP has been successfully modified */
   )
{
   assert(sourcescip != NULL);
   assert(targetscip != NULL);
   assert(neighborhood != NULL);
   assert(targetvars != NULL);
   assert(ndomchgs != NULL);
   assert(nchgobjs != NULL);
   assert(naddedconss != NULL);
   assert(success != NULL);
 
   *success = FALSE;
   *ndomchgs = 0;
   *nchgobjs = 0;
   *naddedconss = 0;
 
   /* call the change sub-SCIP callback of the neighborhood */
   if( neighborhood->changesubscip != NULL )
   {
      SCIP_CALL( neighborhood->changesubscip(sourcescip, targetscip, neighborhood, targetvars, ndomchgs, nchgobjs, naddedconss, success) );
   }
   else
   {
      *success = TRUE;
   }
 
   return SCIP_OKAY;
}
 
/** set sub-SCIP solving limits */
static
SCIP_RETCODE setLimits(
   SCIP*                 subscip,            /**< SCIP data structure */
   SOLVELIMITS*          solvelimits         /**< pointer to solving limits data structure */
   )
{
   assert(subscip != NULL);
   assert(solvelimits != NULL);
 
   assert(solvelimits->nodelimit >= solvelimits->stallnodes);
 
   SCIP_CALL( SCIPsetLongintParam(subscip, "limits/nodes", solvelimits->nodelimit) );
   SCIP_CALL( SCIPsetLongintParam(subscip, "limits/stallnodes", solvelimits->stallnodes));
   SCIP_CALL( SCIPsetRealParam(subscip, "limits/time", solvelimits->timelimit) );
   SCIP_CALL( SCIPsetRealParam(subscip, "limits/memory", solvelimits->memorylimit) );
 
   return SCIP_OKAY;
}
 
/** determine limits for a sub-SCIP */
static
SCIP_RETCODE determineLimits(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEUR*            heur,               /**< this heuristic */
   int                   selection,          /**< index of selected neighborhood */
   SOLVELIMITS*          solvelimits,        /**< pointer to solving limits data structure */
   SCIP_Bool*            runagain            /**< can we solve another sub-SCIP with these limits */
   )
{
   SCIP_HEURDATA* heurdata;
   SCIP_Bool avoidmemout;
 
   assert(scip != NULL);
   assert(heur != NULL);
   assert(solvelimits != NULL);
   assert(runagain != NULL);
 
   heurdata = SCIPheurGetData(heur);
 
   /* set time and memory */
   SCIP_CALL( SCIPgetRealParam(scip, "limits/memory", &solvelimits->memorylimit) );
   SCIP_CALL( SCIPgetBoolParam(scip, "misc/avoidmemout", &avoidmemout) );
   solvelimits->timelimit = heurdata->heurtimelimit;
 
   /* substract the memory already used by the main SCIP and the estimated memory usage of external software */
   if( ! SCIPisInfinity(scip, solvelimits->memorylimit) )
   {
      solvelimits->memorylimit -= SCIPgetMemUsed(scip)/1048576.0;
      solvelimits->memorylimit -= SCIPgetMemExternEstim(scip)/1048576.0;
   }
 
   /* abort if no time is left or not enough memory (we don't abort in this case if misc_avoidmemout == FALSE)
   * to create a copy of SCIP, including external memory usage */
   if( avoidmemout && solvelimits->memorylimit <= 2.0*SCIPgetMemExternEstim(scip)/1048576.0 )
   {
      SCIPdebugMsg(scip, "Aborting LNS heuristic call: Not enough memory or time left.\n");
      *runagain = FALSE;
      return SCIP_OKAY;
   }
 
   solvelimits->stallnodes = -1;
   solvelimits->nodelimit = (SCIP_Longint) heurdata->neighborhoods[selection]->nodelimit;
 
   return SCIP_OKAY;
}
 
/** Calculate reward based on the selected reward measure */
static
SCIP_Real getReward(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data of the scheduler neighborhood */
   int                   selection,          /**< index of selected heuristic */
   HEUR_STATS*           runstats,           /**< run statistics */
   SCIP_STATUS           subscipstatus       /**< status of the sub-SCIP if LNS was used */
   )
{
   SCIP_Real totalreward;
   SCIP_Real effortsaved;
   SCIP_Real bestsolreward;
   SCIP_Real closedgapreward;
   SCIP_Real conflictreward;
 
   /* compute the effort it took to execute selected heuristic */
   if( selection < heurdata->ndiving )
      effortsaved = (SCIP_Real) runstats->divingdepth / (SCIP_Real)heurdata->maxdivingnodelimit;
   else
      effortsaved = MIN(1.0, (SCIP_Real) runstats->usednodes / (SCIP_Real)heurdata->maxlnsnodelimit);
   effortsaved = (1.0 - effortsaved);
 
   /* if LNS heuristic terminated because of the time limit, punish it */
   if( selection > heurdata->ndiving && subscipstatus == SCIP_STATUS_TIMELIMIT )
      effortsaved = 0.0;
 
   assert(effortsaved >= 0.0 && effortsaved <= 1.0);
   assert(heurdata->maxlnsnodelimit > 0);
   assert(heurdata->maxdivingnodelimit > 0);
 
   /* compute reward for number of conflicts generated */
   if( selection < heurdata->ndiving )
   {
      if( runstats->nconflicts == 0 )
         conflictreward = 0.0;
      else if( heurdata->maxnconflicts > 0 )
         conflictreward = (SCIP_Real) runstats->nconflicts / (SCIP_Real) heurdata->maxnconflicts;
      else
         conflictreward = 1.0;
   }
   else
      conflictreward = 0.0; /* LNS heuristics don't add conflict constraints */
   assert(conflictreward >= 0.0 && conflictreward <= 1.0);
 
   /* a positive reward is only assigned if a new incumbent solution was found */
   if( runstats->nbestsolsfound > 0 )
   {
      SCIP_Real lb;
      SCIP_Real ub;
 
      /* the indicator function is simply 1.0 */
      bestsolreward = 1.0;
 
      ub = runstats->newupperbound;
      lb = SCIPgetLowerbound(scip);
 
      /* compute the closed gap reward */
      if( SCIPisEQ(scip, ub, lb) || SCIPisInfinity(scip, runstats->oldupperbound) ) // gap is closed or first primal solution was found
         closedgapreward = 1.0;
      else
         closedgapreward = (runstats->oldupperbound - ub) / (runstats->oldupperbound - lb);
   }
   else
   {
      bestsolreward = 0.0;
      closedgapreward = 0.0;
   }
 
   /* compute total reward */
   totalreward = heurdata->effortrewardweight * effortsaved + heurdata->solrewardweight * bestsolreward
         + heurdata->qualrewardweight * closedgapreward + heurdata->conflictrewardweight * conflictreward;
   totalreward = MIN( totalreward, 1.0);
   assert(totalreward >= 0.0 && totalreward <= 1.0);
 
   return totalreward;
}
 
/** set up the sub-SCIP parameters, objective cutoff, and solution limits */
static
SCIP_RETCODE setupSubScip(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP*                 subscip,            /**< sub-SCIP data structure */
   SCIP_VAR**            subvars,            /**< array of sub-SCIP variables in the order of the main SCIP */
   SOLVELIMITS*          solvelimits,        /**< pointer to solving limits data structure */
   SCIP_HEUR*            heur,               /**< this heuristic */
   SCIP_Bool             objchgd             /**< did the objective change between the source and the target SCIP? */
   )
{
   SCIP_HEURDATA* heurdata;
   SCIP_Real cutoff;
 
   heurdata = SCIPheurGetData(heur);
 
   /* do not abort subproblem on CTRL-C */
   SCIP_CALL( SCIPsetBoolParam(subscip, "misc/catchctrlc", FALSE) );
 
   /* disable output to console unless we are in debug mode */
   SCIP_CALL( SCIPsetIntParam(subscip, "display/verblevel", 0) );
 
   /* disable statistic timing inside sub SCIP */
   SCIP_CALL( SCIPsetBoolParam(subscip, "timing/statistictiming", FALSE) );
 
#ifdef SCHEDULER_SUBSCIPOUTPUT
   SCIP_CALL( SCIPsetIntParam(subscip, "display/verblevel", 5) );
   SCIP_CALL( SCIPsetIntParam(subscip, "display/freq", 1) );
   /* enable statistic timing inside sub SCIP */
      SCIP_CALL( SCIPsetBoolParam(subscip, "timing/statistictiming", TRUE) );
#endif
 
   SCIP_CALL( SCIPsetIntParam(subscip, "limits/bestsol", heurdata->nsolslim) );
 
   /* forbid recursive call of heuristics and separators solving subMIPs */
   if( ! heurdata->usesubscipheurs )
   {
      SCIP_CALL( SCIPsetSubscipsOff(subscip, TRUE) );
   }
 
   /* disable cutting plane separation */
   SCIP_CALL( SCIPsetSeparating(subscip, SCIP_PARAMSETTING_OFF, TRUE) );
 
   /* disable expensive presolving */
   SCIP_CALL( SCIPsetPresolving(subscip, SCIP_PARAMSETTING_FAST, TRUE) );
 
   /* use best estimate node selection */
   if( SCIPfindNodesel(subscip, "estimate") != NULL && ! SCIPisParamFixed(subscip, "nodeselection/estimate/stdpriority") )
   {
      SCIP_CALL( SCIPsetIntParam(subscip, "nodeselection/estimate/stdpriority", INT_MAX/4) );
   }
 
   /* use inference branching */
   if( SCIPfindBranchrule(subscip, "inference") != NULL && ! SCIPisParamFixed(subscip, "branching/inference/priority") )
   {
      SCIP_CALL( SCIPsetIntParam(subscip, "branching/inference/priority", INT_MAX/4) );
   }
 
   /* enable conflict analysis and restrict conflict pool */
   if( ! SCIPisParamFixed(subscip, "conflict/enable") )
   {
      SCIP_CALL( SCIPsetBoolParam(subscip, "conflict/enable", TRUE) );
   }
 
   if( !SCIPisParamFixed(subscip, "conflict/useboundlp") )
   {
      SCIP_CALL( SCIPsetCharParam(subscip, "conflict/useboundlp", 'o') );
   }
 
   if( ! SCIPisParamFixed(subscip, "conflict/maxstoresize") )
   {
      SCIP_CALL( SCIPsetIntParam(subscip, "conflict/maxstoresize", 100) );
   }
 
   /* speed up sub-SCIP by not checking dual LP feasibility */
   SCIP_CALL( SCIPsetBoolParam(subscip, "lp/checkdualfeas", FALSE) );
 
   /* add an objective cutoff */
   if( ! SCIPisInfinity(scip, SCIPgetUpperbound(scip)) )
   {
      cutoff = SCIPgetUpperbound(scip) - SCIPsumepsilon(scip);
 
      /* if the objective changed between the source and the target SCIP, encode the cutoff as a constraint */
      if( ! objchgd )
      {
         SCIP_CALL(SCIPsetObjlimit(subscip, cutoff));
      }
      else
      {
         SCIP_CONS* objcons;
         int nvars;
         SCIP_VAR** vars;
         int i;
 
         vars = SCIPgetVars(scip);
         nvars = SCIPgetNVars(scip);
 
         SCIP_CALL( SCIPcreateConsLinear(subscip, &objcons, "objbound_of_origscip", 0, NULL, NULL, -SCIPinfinity(subscip), cutoff,
                     TRUE, TRUE, TRUE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE) );
         for( i = 0; i < nvars; ++i)
         {
            if( ! SCIPisFeasZero(subscip, SCIPvarGetObj(vars[i])) )
            {
               assert(subvars[i] != NULL);
               SCIP_CALL( SCIPaddCoefLinear(subscip, objcons, subvars[i], SCIPvarGetObj(vars[i])) );
            }
         }
         SCIP_CALL( SCIPaddCons(subscip, objcons) );
         SCIP_CALL( SCIPreleaseCons(subscip, &objcons) );
      }
   }
 
   /* set solve limits for sub-SCIP */
   SCIP_CALL( setLimits(subscip, solvelimits) );
 
   /* change random seed of sub-SCIP */
   if( heurdata->subsciprandseeds )
   {
      SCIP_CALL( SCIPsetIntParam(subscip, "randomization/randomseedshift", (int)SCIPheurGetNCalls(heur)) );
   }
 
   return SCIP_OKAY;
}
 
/** initialize solving frequency */
static
void initSolveFreq(
   SOLVEFREQ*            solvefreqdata       /**< diving heuristic solving freq data */
   )
{
   assert(solvefreqdata != NULL);
 
   /* initialize solve frequency data */
   solvefreqdata->increment = SOLVEFREQ_STARTINC;
   solvefreqdata->maxsolvefreq = MAXSOLVEFREQ;
   solvefreqdata->minsolvefreq = MINSOLVEFREQ;
 
   /* always start with the most conservative value */
   solvefreqdata->currentsolvefreq = solvefreqdata->minsolvefreq;
}
 
/** update increment for solving frequency */
static
void updateSolveFreqIncrement(
   SOLVEFREQ*            solvefreqdata       /**< diving heuristic solving freq data */
   )
{
   solvefreqdata->increment *= SOLVEFREQ_DECAY;
   solvefreqdata->increment = MAX(solvefreqdata->increment, LRATEMIN);
}
 
/** increase solving frequency
 *
 *  decrease also the rate by which the solving frequency is adjusted
 */
static
void increaseSolveFreq(
   SOLVEFREQ*            solvefreqdata       /**< diving heuristic solving freq data */
   )
{
   solvefreqdata->currentsolvefreq += solvefreqdata->increment;
   solvefreqdata->currentsolvefreq = MIN(solvefreqdata->currentsolvefreq, solvefreqdata->maxsolvefreq);
}
 
/** decrease solving frequency
 *
 *  decrease also the rate by which the solving frequency is adjusted
 */
static
void decreaseSolveFreq(
   SOLVEFREQ*            solvefreqdata       /**< diving heuristic solving freq data */
   )
{
   solvefreqdata->currentsolvefreq -= solvefreqdata->increment;
   solvefreqdata->currentsolvefreq = MAX(solvefreqdata->currentsolvefreq, solvefreqdata->minsolvefreq);
}
 
/** update solve frequency for diving heuristics */
static
void updateSolveFreq(
   DIVING_HEUR*          divingheur,         /**< diving heuristic */
   HEUR_STATS*           stats               /**< run statistics for this run */
   )
{
   /* find out why diving heuristic terminated and adapt resolve frequency accordingly */
   if( (int) stats->nprobnodes == divingheur->nodelimit )
      increaseSolveFreq(divingheur->solvefreqdata);
   else if( stats->nsolsfound == 0 )
      decreaseSolveFreq(divingheur->solvefreqdata);
 
   updateSolveFreqIncrement(divingheur->solvefreqdata);
}
 
/** find publicly available divesets and store them */
static
SCIP_RETCODE includeDivingHeurs(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEUR*            heur,               /**< the heuristic */
   SCIP_HEURDATA*        heurdata            /**< heuristic data */
   )
{
   int h;
   SCIP_HEUR** heurs;
 
   assert(scip != NULL);
   assert(heur != NULL);
   assert(heurdata != NULL);
 
   heurs = SCIPgetHeurs(scip);
 
   heurdata->divingheurssize = DIVINGHEURS_INITIALSIZE;
   SCIP_CALL( SCIPallocBlockMemoryArray(scip, &heurdata->divingheurs, heurdata->divingheurssize) );
   heurdata->ndiving = 0;
 
   for( h = 0; h < SCIPgetNHeurs(scip); ++h )
   {
      int d;
      assert(heurs[h] != NULL);
 
      /* loop over divesets of this heuristic and check whether they are public */
      for( d = 0; d < SCIPheurGetNDivesets(heurs[h]); ++d )
      {
         SCIP_DIVESET* diveset = SCIPheurGetDivesets(heurs[h])[d];
 
         if( SCIPdivesetIsPublic(diveset) )
         {
            DIVING_HEUR* divingheur;
 
            SCIPdebugMsg(scip, "Found publicly available diveset %s\n", SCIPdivesetGetName(diveset));
 
            /* allocate memory for the diving heuristic */
            SCIP_CALL( SCIPallocBlockMemory(scip, &divingheur) );
            SCIP_CALL( SCIPallocBlockMemory(scip, &(divingheur->stats)) );
            SCIP_CALL( SCIPallocBlockMemory(scip, &(divingheur->solvefreqdata)) );
 
            /* fill struct with diving heuristic specific information */
            divingheur->diveset = diveset;
            divingheur->nodelimit = heurdata->initdivingnodelimit;
            divingheur->rootnodepriority = SCIPheurGetPriority(heurs[h]);
            divingheur->priority = 1.0;
 
            initSolveFreq(divingheur->solvefreqdata);
            SCIP_CALL( SCIPcreateClock(scip, &(divingheur->stats->setupclock)) );
            SCIP_CALL( SCIPcreateClock(scip, &(divingheur->stats->execclock)) );
            SCIP_CALL( heurStatsReset(scip, divingheur->stats, TRUE) );
 
            if( heurdata->ndiving == heurdata->divingheurssize )
            {
               int newsize = 2 * heurdata->divingheurssize;
               SCIP_CALL( SCIPreallocBlockMemoryArray(scip, &heurdata->divingheurs, heurdata->divingheurssize, newsize) );
               heurdata->divingheurssize = newsize;
            }
            assert( heurdata->ndiving < heurdata->divingheurssize );
 
            heurdata->divingheurs[heurdata->ndiving] = divingheur;
            heurdata->ndiving++;
         }
         else
         {
            SCIPdebugMsg(scip, "Skipping private diveset %s\n", SCIPdivesetGetName(diveset));
         }
      }
   }
   return SCIP_OKAY;
}
 
/** select a heuristic depending on the selected bandit algorithm */
static
SCIP_RETCODE selectHeuristic(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data of the scheduler heuristic */
   int*                  selection           /**< pointer to store the selected heuristic index */
   )
{
   SCIP_BANDIT* bandit;
   int nactions;
 
   assert(scip != NULL);
   assert(heurdata != NULL);
   assert(selection != NULL);
 
   *selection = -1;
   bandit = heurdata->bandit;
   nactions = heurdata->ndiving + heurdata->nactiveneighborhoods;
 
   /* if we use default priorities for executing heuristics for the first time, we don't have to call
    * the bandit to select next action */
   if( heurdata->defaultroot && heurdata->counter < nactions )
   {
      *selection = heurdata->sortedindices[heurdata->counter];
      heurdata->counter++;
   }
   else
   {
      SCIP_CALL( SCIPbanditSelect(bandit, selection) );
   }
   assert(*selection >= 0);
   assert(*selection < heurdata->nactiveneighborhoods + heurdata->ndiving);
 
   return SCIP_OKAY;
}
 
/** update selection strategy with observed reward for future draws */
static
SCIP_RETCODE updateSelectionStrategy(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data of the scheduler heuristic */
   SCIP_Real             reward,             /**< measured reward */
   int                   selection           /**< the heuristic index that was chosen */
   )
{
   SCIP_BANDIT* bandit;
 
   assert(scip != NULL);
   assert(heurdata != NULL);
   assert(selection >= 0);
   assert(selection < heurdata->nneighborhoods + heurdata->ndiving);
 
   bandit = heurdata->bandit;
 
   SCIPdebugMsg(scip, "Rewarding bandit algorithm action %d with reward %.2f\n", selection, reward);
   SCIP_CALL( SCIPbanditUpdate(bandit, selection, reward) );
 
   return SCIP_OKAY;
}
 
/** execute diving heuristic */
static
SCIP_RETCODE executeDivingHeuristic(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEUR*            heur,               /**< scheduler heuristic */
   int                   selection,          /**< the heuristic index that was chosen */
   HEUR_STATS*           runstats,           /**< statistics of the call to selection */
   SCIP_RESULT*          result              /**< pointer to store the result of the heuristic call */
   )
{
   SCIP_HEURDATA* heurdata;
   DIVING_HEUR** divingheurs;
   SCIP_DIVESET* diveset;
 
   heurdata = SCIPheurGetData(heur);
   assert(heurdata != NULL);
 
   divingheurs = heurdata->divingheurs;
   assert(divingheurs != NULL);
   assert(heurdata->ndiving > 0);
   assert(selection < heurdata->ndiving);
   assert(divingheurs[selection] != NULL);
 
   diveset = divingheurs[selection]->diveset;
   assert(diveset != NULL);
 
   SCIPdebugMsg(scip, "Selected diving heuristic %s (idx: %d)\n", SCIPdivesetGetName(diveset), selection);
 
   /* store some data beforehand to track all improvemnts */
   runstats->nbacktracks = SCIPdivesetGetNBacktracks(diveset, SCIP_DIVECONTEXT_SCHEDULER);
   runstats->nconflicts = SCIPdivesetGetNConflicts(diveset, SCIP_DIVECONTEXT_SCHEDULER);
   runstats->nprobnodes = SCIPdivesetGetNProbingNodes(diveset, SCIP_DIVECONTEXT_SCHEDULER);
   runstats->nsolsfound = SCIPdivesetGetNSols(diveset, SCIP_DIVECONTEXT_SCHEDULER);
   runstats->nbestsolsfound = SCIPgetNBestSolsFound(scip);
   runstats->oldupperbound = SCIPgetUpperbound(scip);
 
   if( strcmp(SCIPdivesetGetName(diveset), "guideddiving") != 0 || (strcmp(SCIPdivesetGetName(diveset), "guideddiving") == 0
         && SCIPgetNSols(scip) != 0 && !SCIPsolIsOriginal(SCIPgetBestSol(scip))) )
   {
      SCIP_CALL( SCIPstartClock(scip, divingheurs[selection]->stats->execclock) );
 
      /* perform dive */
      SCIP_CALL( SCIPperformGenericDivingAlgorithm(scip, divingheurs[selection]->diveset, heurdata->sol, heur,
            result, FALSE, -1LL, (int) divingheurs[selection]->nodelimit,
            divingheurs[selection]->solvefreqdata->currentsolvefreq, SCIP_DIVECONTEXT_SCHEDULER) );
 
      SCIP_CALL( SCIPstopClock(scip, divingheurs[selection]->stats->execclock) );
   }
 
   /* store improvements (if solution was found, what solution was found, nconflict constraints, etc.) */
   runstats->nbacktracks = SCIPdivesetGetNBacktracks(diveset, SCIP_DIVECONTEXT_SCHEDULER) - runstats->nbacktracks;
   runstats->nconflicts = SCIPdivesetGetNConflicts(diveset, SCIP_DIVECONTEXT_SCHEDULER) - runstats->nconflicts;
   runstats->nprobnodes = SCIPdivesetGetNProbingNodes(diveset, SCIP_DIVECONTEXT_SCHEDULER) - runstats->nprobnodes;
   runstats->nsolsfound = SCIPdivesetGetNSols(diveset, SCIP_DIVECONTEXT_SCHEDULER) - runstats->nsolsfound;
   runstats->nbestsolsfound = SCIPgetNBestSolsFound(scip) - runstats->nbestsolsfound;
   runstats->newupperbound = SCIPgetUpperbound(scip);
 
   /* update maximum number of conflicts found */
   heurdata->maxnconflicts = MAX(heurdata->maxnconflicts, (int) runstats->nconflicts);
 
   SCIPdebugMsg(scip, "Finished executing diving heuristic %s (idx: %d) with %lld sols (%lld best sols), %lld conflicts, %lld backtracks and %lld probing nodes \n",
         SCIPdivesetGetName(diveset), selection, runstats->nsolsfound, runstats->nbestsolsfound,
         runstats->nconflicts, runstats->nbacktracks, runstats->nprobnodes);
 
   if( runstats->nbestsolsfound > 0 )
      SCIPdebugMsg(scip, "Upperbound changed: %g -> %g\n", runstats->oldupperbound, runstats->newupperbound);
 
   assert( runstats->nbestsolsfound == 0 || runstats->oldupperbound > runstats->newupperbound );
 
   return SCIP_OKAY;
}
 
/** execute LNS heuristic */
static
SCIP_RETCODE executeLNSHeuristic(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEUR*            heur,               /**< scheduler heuristic */
   int                   selection,          /**< the heuristic index that was chosen */
   HEUR_STATS*           runstats,           /**< statistics of the call to selection */
   SCIP_STATUS*          subscipstatus,      /**< pointer to store status of the sub-SCIP solve */
   SCIP_RESULT*          result              /**< pointer to store the result of the heuristic call */
   )
{
   SCIP_HEURDATA* heurdata;
   SCIP_VAR** varbuf;
   SCIP_Real* valbuf;
   SCIP_VAR** vars;
   SCIP_VAR** subvars;
   SCIP* subscip = NULL;
 
   int nfixings;
   int nvars;
   NH* neighborhood;
   SOLVELIMITS solvelimits;
   SCIP_Bool success;
   SCIP_Bool run;
 
   SCIP_HASHMAP* varmapf;
   SCIP_EVENTHDLR* eventhdlr;
   SCIP_EVENTDATA eventdata;
   char probnamesuffix[SCIP_MAXSTRLEN];
   int ndomchgs;
   int nchgobjs;
   int naddedconss;
   int v;
   SCIP_RETCODE retcode;
   SCIP_RESULT fixresult;
 
   heurdata = SCIPheurGetData(heur);
   assert(heurdata != NULL);
 
   *result = SCIP_DIDNOTRUN;
   *subscipstatus = SCIP_STATUS_UNKNOWN;
   run = TRUE;
 
   SCIPdebugMsg(scip, "Selected LNS heuristic %s (idx: %d)\n", heurdata->neighborhoods[selection]->name, selection + heurdata->ndiving);
 
   /* check if budget allows a run of the next selected neighborhood */
   SCIP_CALL( determineLimits(scip, heur, selection, &solvelimits, &run) );
 
   if( ! run )
      return SCIP_OKAY;
 
   /* allocate memory for variable fixings buffer */
   SCIP_CALL( SCIPgetVarsData(scip, &vars, &nvars, NULL, NULL, NULL, NULL) );
   SCIP_CALL( SCIPallocBufferArray(scip, &varbuf, nvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &valbuf, nvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &subvars, nvars) );
 
   neighborhood = heurdata->neighborhoods[selection];
   SCIPdebugMsg(scip, "Running '%s' neighborhood %d\n", neighborhood->name, selection);
 
   SCIP_CALL( SCIPstartClock(scip, neighborhood->stats.setupclock) );
 
   /* determine variable fixings and objective coefficients of this neighborhood */
   SCIP_CALL( neighborhoodFixVariables(scip, heurdata, neighborhood, varbuf, valbuf, &nfixings, &fixresult) );
 
   SCIPdebugMsg(scip, "Fix %d/%d variables, result code %d\n", nfixings, nvars, fixresult);
 
   /* Fixing was not successful, either because the fixing rate was not reached (and no additional variable
    * prioritization was used), or the neighborhood requested a delay, e.g., because no LP relaxation solution exists
    * at the current node
    *
    * The scheduler heuristic keeps a delayed neighborhood active and delays itself.
    * TODO: handle delays
    */
   if( fixresult != SCIP_SUCCESS )
   {
      SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.setupclock) );
 
      SCIPdebugMsg(scip, "Aborting LNS heuristic call: Not enough variables fixed.\n");
 
      *result = fixresult;
      goto CLEANUP;
   }
 
   *result = SCIP_DIDNOTFIND;
 
   neighborhood->stats.nfixings += nfixings;
   runstats->nfixings = nfixings;
 
   SCIP_CALL( SCIPcreate(&subscip) );
   SCIP_CALL( SCIPhashmapCreate(&varmapf, SCIPblkmem(scip), nvars) );
   (void) SCIPsnprintf(probnamesuffix, SCIP_MAXSTRLEN, "scheduler_%s", neighborhood->name);
 
   /* todo later: run global propagation for this set of fixings */
   SCIP_CALL( SCIPcopyLargeNeighborhoodSearch(scip, subscip, varmapf, probnamesuffix, varbuf, valbuf, nfixings, FALSE, heurdata->copycuts, &success, NULL) );
 
   /* store sub-SCIP variables in array for faster access */
   for( v = 0; v < nvars; ++v )
   {
      subvars[v] = (SCIP_VAR*)SCIPhashmapGetImage(varmapf, (void *)vars[v]);
   }
 
   SCIPhashmapFree(&varmapf);
 
   /* let the neighborhood add additional constraints, or restrict domains */
   SCIP_CALL( neighborhoodChangeSubscip(scip, subscip, neighborhood, subvars, &ndomchgs, &nchgobjs, &naddedconss, &success) );
 
   if( ! success )
   {
      SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.setupclock) );
      SCIPdebugMsg(scip, "Aborting LNS heuristic call: Problems with creating subproblem.\n");
      goto CLEANUP;
   }
 
   /* set up sub-SCIP parameters */
   SCIP_CALL( setupSubScip(scip, subscip, subvars, &solvelimits, heur, nchgobjs > 0) );
 
   /* copy the necessary data into the event data to create new solutions */
   eventdata.nodelimit = solvelimits.nodelimit;  /*lint !e644*/
   eventdata.lplimfac = heurdata->lplimfac;
   eventdata.heur = heur;
   eventdata.sourcescip = scip;
   eventdata.subvars = subvars;
   eventdata.runstats = runstats;
 
   /* include an event handler to transfer solutions into the main SCIP */
   SCIP_CALL( SCIPincludeEventhdlrBasic(subscip, &eventhdlr, EVENTHDLR_NAME, EVENTHDLR_DESC, eventExecScheduler, NULL) );
 
   /* transform the problem before catching the events */
   SCIP_CALL( SCIPtransformProb(subscip) );
   SCIP_CALL( SCIPcatchEvent(subscip, SCIP_EVENTTYPE_SCHEDULER, eventhdlr, &eventdata, NULL) );
 
   SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.setupclock) );
 
   SCIP_CALL( SCIPstartClock(scip, neighborhood->stats.execclock) );
 
   /* set up sub-SCIP and run presolving */
   retcode = SCIPpresolve(subscip);
   if( retcode != SCIP_OKAY )
   {
      SCIPwarningMessage(scip, "Error while presolving subproblem in Scheduler heuristic; sub-SCIP terminated with code <%d>\n", retcode);
      SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.execclock) );
 
      SCIPABORT();  /*lint --e{527}*/
      goto CLEANUP;
   }
 
   /* run sub-SCIP for the given budget, and collect statistics */
   SCIP_CALL_ABORT( SCIPsolve(subscip) );
 
#ifdef SCHEDULER_SUBSCIPOUTPUT
   SCIP_CALL( SCIPprintStatistics(subscip, NULL) );
#endif
 
   SCIP_CALL( SCIPstopClock(scip, neighborhood->stats.execclock) );
 
   /* update statistics based on the sub-SCIP run results */
   updateRunStats(runstats, subscip);
   *subscipstatus = SCIPgetStatus(subscip);
   SCIPdebugMsg(scip, "Status of sub-SCIP run: %d\n", *subscipstatus);
 
CLEANUP:
   if( subscip != NULL )
   {
      SCIP_CALL( SCIPfree(&subscip) );
   }
 
   SCIPfreeBufferArray(scip, &subvars);
   SCIPfreeBufferArray(scip, &valbuf);
   SCIPfreeBufferArray(scip, &varbuf);
 
   if( *result != SCIP_DELAYED && *result != SCIP_DIDNOTRUN )
   {
      /* decrease the number of neighborhoods that have not been initialized */
      if( neighborhood->stats.nruns == 0 )
         --heurdata->ninitneighborhoods;
 
      heurdata->usednodes += runstats->usednodes;
 
      SCIPdebugMsg(scip, "Finished executing LNS heuristic %s (idx: %d) with %lld sols (%lld best sols) and %lld nodes used.\n",
            neighborhood->name, selection + heurdata->ndiving, runstats->nsolsfound, runstats->nbestsolsfound, runstats->usednodes);
 
      if( runstats->nbestsolsfound > 0 )
         SCIPdebugMsg(scip, "Upperbound changed: %g -> %g\n", runstats->oldupperbound, SCIPgetUpperbound(scip));
 
      resetCurrentNeighborhood(heurdata);
   }
 
   return SCIP_OKAY;
}
 
/** execute selected heuristic */
static
SCIP_RETCODE executeHeuristic(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEUR*            heur,               /**< scheduler heuristic */
   int                   selection,          /**< the heuristic index that was chosen */
   HEUR_STATS*           runstats,           /**< statistics of call to selection */
   SCIP_STATUS*          subscipstatus,      /**< pointer to store status of the sub-SCIP solve or NULL if diving was used */
   SCIP_RESULT*          result              /**< pointer to store the result of the heuristic call */
   )
{
   SCIP_HEURDATA* heurdata;
 
   heurdata = SCIPheurGetData(heur);
   assert(heurdata != NULL);
   assert(scip != NULL);
   assert(selection >= 0);
   assert(selection < heurdata->nneighborhoods + heurdata->ndiving);
 
   /* check if a diving or LNS heuristic was selected */
   if( selection < heurdata->ndiving )
   {
      SCIP_CALL( executeDivingHeuristic(scip, heur, selection, runstats, result) );
   }
   else
   {
      SCIP_CALL( executeLNSHeuristic(scip, heur, selection - heurdata->ndiving, runstats, subscipstatus, result) );
   }
 
   return SCIP_OKAY;
}
 
/** reinitialize bandit algorithm since the number of actions has changed */
static
SCIP_RETCODE reinitBandit(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata,           /**< heuristic data */
   int                   nactions            /**< new number of actions */
   )
{
   SCIP_Real* priorities;
   int i;
   unsigned int initseed;
 
   /* allocate memory for the priorities */
   SCIP_CALL( SCIPallocBufferArray(scip, &priorities, nactions) );
 
   /* get the priorities */
   for( i = 0; i < heurdata->ndiving; ++i )
      priorities[i] = heurdata->divingheurs[i]->priority;
   for( i = 0; i < heurdata->nactiveneighborhoods; ++i )
      priorities[i + heurdata->ndiving] = heurdata->neighborhoods[i]->priority;
 
   /* free bandit if necessary */
   if( heurdata->bandit != NULL )
   {
      SCIP_CALL( SCIPfreeBandit(scip, &heurdata->bandit) );
      heurdata->bandit = NULL;
   }
 
   /* create bandit again */
   initseed = (unsigned int)(heurdata->seed + SCIPgetNVars(scip));
   SCIP_CALL( createBandit(scip, heurdata, priorities, initseed) );
   resetTargetNodeLimit(heurdata);
 
   /* free memory */
   SCIPfreeBufferArray(scip, &priorities);
 
   return SCIP_OKAY;
}
 
/** initializes everything that was missing because diving heuristics were not proccessed by SCIP yet. In particular,
 * the function adds diving heuristics to heurdata, heurdata->maxdivingnodelimit,
 * heurdata->maxlnsnodelimit and heurdata->sortedindices if heurdata->defaultroot is set to TRUE
 */
static
SCIP_RETCODE initRest(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEUR*            heur                /**< scheduler heuristic */
   )
{
   SCIP_HEURDATA* heurdata;
   SCIP_Real* priorities;
   int nheurs;
   int i;
 
   /* get heuristic data */
   heurdata = SCIPheurGetData(heur);
 
   /* include the diving heuristics */
   SCIP_CALL( includeDivingHeurs(scip, heur, heurdata) );
 
   /* get number of active heuristics we can choose from */
   nheurs = heurdata->ndiving + heurdata->nactiveneighborhoods;
 
   /* we need to initialize the bandit method again since the number of actions has changed */
   SCIP_CALL( reinitBandit(scip, heurdata, nheurs) );
 
   /* set maximum of all node and diving depth limit */
   heurdata->maxdivingnodelimit = heurdata->initdivingnodelimit;
   heurdata->maxlnsnodelimit = heurdata->initlnsnodelimit;
 
   /* initialize nodelimit for all LNS heursitics  */
   for( i = 0; i < heurdata->nactiveneighborhoods; ++i )
      heurdata->neighborhoods[i]->nodelimit = heurdata->initlnsnodelimit;
 
   /* initialize indices array and sort according to heuristic's priorities if we want to execute heuristics in default order
    * at the root node*/
   if( heurdata->defaultroot )
   {
      SCIP_CALL( SCIPallocBlockMemoryArray(scip, &heurdata->sortedindices, heurdata->ndiving + heurdata->nneighborhoods) );
      SCIP_CALL( SCIPallocBufferArray(scip, &priorities, nheurs) );
      heurdata->counter = 0;
 
      for( i = 0; i < nheurs; ++i )
      {
         heurdata->sortedindices[i] = i;
 
         if( i < heurdata->ndiving )
            priorities[i] = (SCIP_Real)-heurdata->divingheurs[i]->rootnodepriority;
         else
            priorities[i] = (SCIP_Real)-heurdata->neighborhoods[i - heurdata->ndiving]->rootnodepriority;
      }
 
      /* sort indices */
      SCIPsortRealInt(priorities, heurdata->sortedindices, nheurs);
 
      SCIPfreeBufferArray(scip, &priorities);
   }
 
   return SCIP_OKAY;
}
 
/** execution method of primal heuristic */
static
SCIP_DECL_HEUREXEC(heurExecScheduler)
{  /*lint --e{715}*/
   SCIP_HEURDATA* heurdata;
   SCIP_Bool success;
 
   assert(heur != NULL);
   assert(strcmp(SCIPheurGetName(heur), HEUR_NAME) == 0);
   assert(scip != NULL);
   assert(result != NULL);
 
   /* get heuristic data */
   heurdata = SCIPheurGetData(heur);
 
   SCIPdebugMsg(scip, "Calling heurExecScheduler: depth %d sols %d inf %u node %lld \n",
         SCIPgetDepth(scip), SCIPgetNSols(scip), nodeinfeasible, SCIPgetNNodes(scip));
 
   /* store diving heuristics if not done already and reset stats */
   if( heurdata->divingheurs == NULL )
   {
      SCIP_CALL( initRest(scip, heur) );
   }
   assert( heurdata->divingheurs != NULL );
 
   *result = SCIP_DELAYED;
 
   /* do not call heuristic in node that was already detected to be infeasible */
   if( nodeinfeasible )
      return SCIP_OKAY;
 
   /* only call heuristic, if an optimal LP solution is at hand */
   if( !SCIPhasCurrentNodeLP(scip) || SCIPgetLPSolstat(scip) != SCIP_LPSOLSTAT_OPTIMAL )
      return SCIP_OKAY;
 
   /* only call heuristic, if the LP objective value is smaller than the cutoff bound */
   if( SCIPisGE(scip, SCIPgetLPObjval(scip), SCIPgetCutoffbound(scip)) )
      return SCIP_OKAY;
 
   /* only call heuristic, if the LP solution is basic (which allows fast resolve in diving) */
   if( !SCIPisLPSolBasic(scip) )
      return SCIP_OKAY;
 
   /* update internal incumbent solution */
   if( SCIPgetBestSol(scip) != heurdata->lastcallsol )
   {
      heurdata->lastcallsol = SCIPgetBestSol(scip);
      heurdata->firstcallthissol = SCIPheurGetNCalls(heur);
   }
 
   /* do not run more than a user-defined number of times on each incumbent (-1: no limit) */
   if( heurdata->maxcallssamesol != -1 )
   {
      SCIP_Longint samesollimit;
 
      /* either it is the user-defined limit or the number of heuristics controlled by the scheduler */
      samesollimit = (heurdata->maxcallssamesol > 0) ? heurdata->maxcallssamesol : (SCIP_Longint) heurdata->nneighborhoods + heurdata->ndiving;
 
      if( SCIPheurGetNCalls(heur) - heurdata->firstcallthissol >= samesollimit )
      {
         SCIPdebugMsg(scip, "Heuristic already called %" SCIP_LONGINT_FORMAT " times on current incumbent\n", SCIPheurGetNCalls(heur) - heurdata->firstcallthissol);
         return SCIP_OKAY;
      }
   }
 
   /* wait for a sufficient number of nodes since last incumbent solution */
   if( SCIPgetDepth(scip) > 0 && SCIPgetBestSol(scip) != NULL
      && (SCIPgetNNodes(scip) - SCIPsolGetNodenum(SCIPgetBestSol(scip))) < heurdata->waitingnodes )
   {
      SCIPdebugMsg(scip, "Waiting nodes not satisfied\n");
      return SCIP_OKAY;
   }
 
   /* skip this call if scheduler was too unsuccessful in the past few calls */
   if( heurdata->nskippedcalls > 0 )
   {
      /* reduce counter because we need to skip one call less now */
      heurdata->nskippedcalls--;
 
      return SCIP_OKAY;
   }
   else
   {
      /* check if we need to skip calls in the future */
      heurdata->nskippedcalls = (int) floor(exp(0.1 * (SCIP_Real) heurdata->nfailedcalls)) - 1;
   }
 
   *result = SCIP_DIDNOTRUN;
   success = FALSE;
   {
      int selection;
      SCIP_Real reward;
      HEUR_STATS* stats;
      SCIP_STATUS subscipstatus;
 
      subscipstatus = SCIP_STATUS_UNKNOWN;
 
      /* allocate memory for statistics and initialize it */
      SCIP_CALL( SCIPallocBuffer(scip, &stats) );
      initRunStats(scip, stats);
 
      /* select the heuristic based on previous success. The heuristics are sorted such that
       * diving comes before LNS */
      SCIP_CALL( selectHeuristic(scip, heurdata, &selection) );
 
      /* execute selected heuristic */
      SCIP_CALL( executeHeuristic(scip, heur, selection, stats, &subscipstatus, result) );
 
      /* update global statistics */
      if( selection < heurdata->ndiving ) /* diving was selected */
         updateHeurStatsDiving(stats, heurdata->divingheurs[selection]);
      else /* LNS was selected */
         updateHeurStatsLNS(stats, heurdata->neighborhoods[selection - heurdata->ndiving], &subscipstatus);
 
      /* observe reward */
      reward = getReward(scip, heurdata, selection, stats, subscipstatus);
 
      /* call was successfull if solution was found */
      if( stats->nbestsolsfound > 0 )
         success = TRUE;
 
      /* update either LP resolve freq or target fixing rate, depending on which heuristic was chosen */
      if( selection < heurdata->ndiving )
      {
         /* update resolve freq */
         updateSolveFreq(heurdata->divingheurs[selection], stats);
      }
      else
      {
         /* update target fixing rate */
         SCIPdebugMsg(scip, "Update fixing rate: %.2f\n", heurdata->neighborhoods[selection - heurdata->ndiving]->fixingrate.targetfixingrate);
         updateFixingRate(heurdata->neighborhoods[selection - heurdata->ndiving], subscipstatus, stats);
         SCIPdebugMsg(scip, "New fixing rate: %.2f\n", heurdata->neighborhoods[selection - heurdata->ndiving]->fixingrate.targetfixingrate);
      }
 
      /* update selection strategy */
      SCIP_CALL( updateSelectionStrategy(scip, heurdata, reward, selection) );
 
      /* free statistics data struct */
      SCIPfreeBuffer(scip, &stats);
   }
 
   /* count how many consecutive failed calls we had */
   if( success )
      heurdata->nfailedcalls = 0;
   else
      heurdata->nfailedcalls++;
 
   return SCIP_OKAY;
}
 
/** callback to collect variable fixings of RENS */
static
DECL_VARFIXINGS(varFixingsRens)
{  /*lint --e{715}*/
   int nbinvars;
   int nintvars;
   SCIP_VAR** vars;
   int i;
   int *fracidx = NULL;
   SCIP_Real* frac = NULL;
   int nfracs;
 
   assert(scip != NULL);
   assert(varbuf != NULL);
   assert(nfixings != NULL);
   assert(valbuf != NULL);
 
   *result = SCIP_DELAYED;
 
   if( ! SCIPhasCurrentNodeLP(scip) )
      return SCIP_OKAY;
   if( SCIPgetLPSolstat(scip) != SCIP_LPSOLSTAT_OPTIMAL )
      return SCIP_OKAY;
 
   *result = SCIP_DIDNOTRUN;
 
   /* get variable information */
   SCIP_CALL( SCIPgetVarsData(scip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
 
   /* return if no binary or integer variables are present */
   if( nbinvars + nintvars == 0 )
      return SCIP_OKAY;
 
   SCIP_CALL( SCIPallocBufferArray(scip, &fracidx, nbinvars + nintvars) );
   SCIP_CALL( SCIPallocBufferArray(scip, &frac, nbinvars + nintvars) );
 
   /* loop over binary and integer variables; determine those that should be fixed in the sub-SCIP */
   for( nfracs = 0, i = 0; i < nbinvars + nintvars; ++i )
   {
      SCIP_VAR* var = vars[i];
      SCIP_Real lpsolval = SCIPvarGetLPSol(var);
      assert((i < nbinvars && SCIPvarIsBinary(var)) || (i >= nbinvars && SCIPvarIsIntegral(var)));
 
      /* fix all binary and integer variables with integer LP solution value */
      if( SCIPisFeasIntegral(scip, lpsolval) )
      {
         tryAdd2variableBuffer(scip, var, lpsolval, varbuf, valbuf, nfixings, TRUE);
      }
      else
      {
         frac[nfracs] = SCIPfrac(scip, lpsolval);
         frac[nfracs] = MIN(frac[nfracs], 1.0 - frac[nfracs]);
         fracidx[nfracs++] = i;
      }
   }
 
   /* do some additional fixing */
   if( *nfixings < neighborhood->fixingrate.targetfixingrate * (nbinvars + nintvars) && nfracs > 0 )
   {
      SCIPsortDownRealInt(frac, fracidx, nfracs);
 
      /* prefer variables that are almost integer */
      for( i = 0; i < nfracs && *nfixings < neighborhood->fixingrate.targetfixingrate * (nbinvars + nintvars); i++ )
      {
         tryAdd2variableBuffer(scip, vars[fracidx[i]], SCIPround(scip, SCIPvarGetLPSol(vars[fracidx[i]])), varbuf, valbuf, nfixings, TRUE);
      }
   }
 
   SCIPfreeBufferArray(scip, &frac);
   SCIPfreeBufferArray(scip, &fracidx);
 
   *result = SCIP_SUCCESS;
 
   return SCIP_OKAY;
}
 
/** callback for RENS subproblem changes */
static
DECL_CHANGESUBSCIP(changeSubscipRens)
{  /*lint --e{715}*/
   SCIP_VAR** vars;
   int nintvars;
   int nbinvars;
   int i;
 
   assert(SCIPhasCurrentNodeLP(sourcescip));
   assert(SCIPgetLPSolstat(sourcescip) == SCIP_LPSOLSTAT_OPTIMAL);
 
   /* get variable information */
   SCIP_CALL( SCIPgetVarsData(sourcescip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
 
   /* restrict bounds of integer variables with fractional solution value */
   for( i = nbinvars; i < nbinvars + nintvars; ++i )
   {
      SCIP_VAR* var = vars[i];
      SCIP_Real lpsolval = SCIPgetSolVal(sourcescip, NULL, var);
 
      if( subvars[i] == NULL )
         continue;
 
      if( ! SCIPisFeasIntegral(sourcescip, lpsolval) )
      {
         SCIP_Real newlb = SCIPfloor(sourcescip, lpsolval);
         SCIP_Real newub = newlb + 1.0;
 
         /* only count this as a domain change if the new lower and upper bound are a further restriction */
         if( newlb > SCIPvarGetLbGlobal(subvars[i]) + 0.5 || newub < SCIPvarGetUbGlobal(subvars[i]) - 0.5 )
         {
            SCIP_CALL( SCIPchgVarLbGlobal(targetscip, subvars[i], newlb) );
            SCIP_CALL( SCIPchgVarUbGlobal(targetscip, subvars[i], newub) );
            (*ndomchgs)++;
         }
      }
   }
 
   *success = TRUE;
 
   return SCIP_OKAY;
}
 
/** collect fixings by matching solution values in a collection of solutions for all binary and integer variables,
 *  or for a custom set of variables
 */
static
SCIP_RETCODE fixMatchingSolutionValues(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_SOL**            sols,               /**< array of 2 or more solutions. It is okay for the array to contain one element
                                              *   equal to NULL to represent the current LP solution */
   int                   nsols,              /**< number of solutions in the array */
   SCIP_VAR**            vars,               /**< variable array for which solution values must agree */
   int                   nvars,              /**< number of variables, or -1 for all binary and integer variables */
   SCIP_VAR**            varbuf,             /**< buffer storage for variable fixings */
   SCIP_Real*            valbuf,             /**< buffer storage for fixing values */
   int*                  nfixings            /**< pointer to store the number of fixings */
   )
{
   int v;
   int nbinintvars;
   SCIP_SOL* firstsol;
 
   assert(scip != NULL);
   assert(sols != NULL);
   assert(nsols >= 2);
   assert(varbuf != NULL);
   assert(valbuf != NULL);
   assert(nfixings != NULL);
   assert(*nfixings == 0);
 
   if( nvars == -1 || vars == NULL )
   {
      int nbinvars;
      int nintvars;
      SCIP_CALL( SCIPgetVarsData(scip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
      nbinintvars = nbinvars + nintvars;
      nvars = nbinintvars;
   }
   firstsol = sols[0];
   assert(nvars > 0);
 
   /* loop over integer and binary variables and check if their solution values match in all solutions */
   for( v = 0; v < nvars; ++v )
   {
      SCIP_Real solval;
      SCIP_VAR* var;
      int s;
 
      var = vars[v];
      assert((v < SCIPgetNBinVars(scip) && SCIPvarIsBinary(var)) || (v >= SCIPgetNBinVars(scip) && SCIPvarIsIntegral(var)));
      solval = SCIPgetSolVal(scip, firstsol, var);
 
      /* determine if solution values match in all given solutions */
      for( s = 1; s < nsols; ++s )
      {
         SCIP_Real solval2 = SCIPgetSolVal(scip, sols[s], var);
         if( ! SCIPisEQ(scip, solval, solval2) )
            break;
      }
 
      /* if we did not break early, all solutions agree on the solution value of this variable */
      if( s == nsols )
      {
         tryAdd2variableBuffer(scip, var, solval, varbuf, valbuf, nfixings, TRUE);
      }
   }
 
   return SCIP_OKAY;
}
 
/** callback to collect variable fixings of RINS */
static
DECL_VARFIXINGS(varFixingsRins)
{
   /*lint --e{715}*/
   int nbinvars;
   int nintvars;
   SCIP_VAR** vars;
   SCIP_SOL* incumbent;
   SCIP_SOL* sols[2];
   assert(scip != NULL);
   assert(varbuf != NULL);
   assert(nfixings != NULL);
   assert(valbuf != NULL);
 
   *result = SCIP_DELAYED;
 
   if( ! SCIPhasCurrentNodeLP(scip) )
      return SCIP_OKAY;
   if( SCIPgetLPSolstat(scip) != SCIP_LPSOLSTAT_OPTIMAL )
      return SCIP_OKAY;
 
   *result = SCIP_DIDNOTRUN;
 
   incumbent = SCIPgetBestSol(scip);
   if( incumbent == NULL )
      return SCIP_OKAY;
 
   if( SCIPsolGetOrigin(incumbent) == SCIP_SOLORIGIN_ORIGINAL )
      return SCIP_OKAY;
 
   /* get variable information */
   SCIP_CALL( SCIPgetVarsData(scip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
 
   /* return if no binary or integer variables are present */
   if( nbinvars + nintvars == 0 )
      return SCIP_OKAY;
 
   sols[0] = NULL;
   sols[1] = incumbent;
 
   SCIP_CALL( fixMatchingSolutionValues(scip, sols, 2, vars, nbinvars + nintvars, varbuf, valbuf, nfixings) );
 
   *result = SCIP_SUCCESS;
 
   return SCIP_OKAY;
}
 
/** initialization callback for crossover when a new problem is read */
static
DECL_NHINIT(nhInitCrossover)
{  /*lint --e{715}*/
   DATA_CROSSOVER* data;
 
   data = neighborhood->data.crossover;
   assert(data != NULL);
 
   if( data->rng != NULL )
      SCIPfreeRandom(scip, &data->rng);
 
   data->selsol = NULL;
 
   SCIP_CALL( SCIPcreateRandom(scip, &data->rng, CROSSOVERSEED + (unsigned int)SCIPgetNVars(scip), TRUE) );
 
   return SCIP_OKAY;
}
 
/** deinitialization callback for crossover when exiting a problem */
static
DECL_NHEXIT(nhExitCrossover)
{  /*lint --e{715}*/
   DATA_CROSSOVER* data;
   data = neighborhood->data.crossover;
 
   assert(neighborhood != NULL);
   assert(data->rng != NULL);
 
   SCIPfreeRandom(scip, &data->rng);
 
   return SCIP_OKAY;
}
 
/** deinitialization callback for crossover before SCIP is freed */
static
DECL_NHFREE(nhFreeCrossover)
{  /*lint --e{715}*/
   assert(neighborhood->data.crossover != NULL);
   SCIPfreeBlockMemory(scip, &neighborhood->data.crossover);
 
   return SCIP_OKAY;
}
 
/** callback to collect variable fixings of crossover */
static
DECL_VARFIXINGS(varFixingsCrossover)
{  /*lint --e{715}*/
   DATA_CROSSOVER* data;
   SCIP_RANDNUMGEN* rng;
   SCIP_SOL** sols;
   SCIP_SOL** scipsols;
   int nsols;
   int lastdraw;
   assert(scip != NULL);
   assert(varbuf != NULL);
   assert(nfixings != NULL);
   assert(valbuf != NULL);
 
   data = neighborhood->data.crossover;
 
   assert(data != NULL);
   nsols = data->nsols;
   data->selsol = NULL;
 
   *result = SCIP_DIDNOTRUN;
 
   /* return if the pool has not enough solutions */
   if( nsols > SCIPgetNSols(scip) )
      return SCIP_OKAY;
 
   /* return if no binary or integer variables are present */
   if( SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip) == 0 )
      return SCIP_OKAY;
 
   rng = data->rng;
   lastdraw = SCIPgetNSols(scip);
   SCIP_CALL( SCIPallocBufferArray(scip, &sols, nsols) );
   scipsols = SCIPgetSols(scip);
 
   /* draw as many solutions from the pool as required by crossover, biased towards
    * better solutions; therefore, the sorting of the solutions by objective is implicitly used
    */
   while( nsols > 0 )
   {
      /* no need for randomization anymore, exactly nsols many solutions remain for the selection */
      if( lastdraw == nsols )
      {
         int s;
 
         /* fill the remaining slots 0,...,nsols - 1 by the solutions at the same places */
         for( s = 0; s < nsols; ++s )
            sols[s] = scipsols[s];
 
         nsols = 0;
      }
      else
      {
         int nextdraw;
 
         assert(nsols < lastdraw);
 
         /* draw from the lastdraw - nsols many solutions nsols - 1, ... lastdraw - 1 such that nsols many solution */
         nextdraw = SCIPrandomGetInt(rng, nsols - 1, lastdraw - 1);
         assert(nextdraw >= 0);
 
         sols[nsols - 1] = scipsols[nextdraw];
         nsols--;
         lastdraw = nextdraw;
      }
   }
 
   SCIP_CALL( fixMatchingSolutionValues(scip, sols, data->nsols, NULL, -1, varbuf, valbuf, nfixings) );
 
   /* store best selected solution as reference solution */
   data->selsol = sols[0];
   assert(data->selsol != NULL);
 
   *result = SCIP_SUCCESS;
 
   SCIPfreeBufferArray(scip, &sols);
 
   return SCIP_OKAY;
}
 
/** callback for crossover reference solution */
static
DECL_NHREFSOL(nhRefsolCrossover)
{ /*lint --e{715}*/
   DATA_CROSSOVER* data;
 
   data = neighborhood->data.crossover;
 
   if( data->selsol != NULL )
   {
      *solptr = data->selsol;
      *result = SCIP_SUCCESS;
   }
   else
   {
      *result = SCIP_DIDNOTFIND;
   }
 
   return SCIP_OKAY;
}
 
/** initialization callback for mutation when a new problem is read */
static
DECL_NHINIT(nhInitMutation)
{  /*lint --e{715}*/
   DATA_MUTATION* data;
   assert(scip != NULL);
   assert(neighborhood != NULL);
 
   SCIP_CALL( SCIPallocBlockMemory(scip, &neighborhood->data.mutation) );
 
   data = neighborhood->data.mutation;
   assert(data != NULL);
 
   SCIP_CALL( SCIPcreateRandom(scip, &data->rng, MUTATIONSEED + (unsigned int)SCIPgetNVars(scip), TRUE) );
 
   return SCIP_OKAY;
}
 
/** deinitialization callback for mutation when exiting a problem */
static
DECL_NHEXIT(nhExitMutation)
{  /*lint --e{715}*/
   DATA_MUTATION* data;
   assert(scip != NULL);
   assert(neighborhood != NULL);
   data = neighborhood->data.mutation;
   assert(data != NULL);
 
   SCIPfreeRandom(scip, &data->rng);
 
   SCIPfreeBlockMemory(scip, &neighborhood->data.mutation);
 
   return SCIP_OKAY;
}
 
/** callback to collect variable fixings of mutation */
static
DECL_VARFIXINGS(varFixingsMutation)
{  /*lint --e{715}*/
   SCIP_RANDNUMGEN* rng;
 
   SCIP_VAR** vars;
   SCIP_VAR** varscpy;
   int i;
   int nvars;
   int nbinvars;
   int nintvars;
   int nbinintvars;
   int ntargetfixings;
   SCIP_SOL* incumbentsol;
   SCIP_Real targetfixingrate;
 
   assert(scip != NULL);
   assert(neighborhood != NULL);
   assert(neighborhood->data.mutation != NULL);
   assert(neighborhood->data.mutation->rng != NULL);
   rng = neighborhood->data.mutation->rng;
 
   *result = SCIP_DIDNOTRUN;
 
   /* get the problem variables */
   SCIP_CALL( SCIPgetVarsData(scip, &vars, &nvars, &nbinvars, &nintvars, NULL, NULL) );
 
   nbinintvars = nbinvars + nintvars;
   if( nbinintvars == 0 )
      return SCIP_OKAY;
 
   incumbentsol = SCIPgetBestSol(scip);
   if( incumbentsol == NULL )
      return SCIP_OKAY;
 
   targetfixingrate = neighborhood->fixingrate.targetfixingrate;
   ntargetfixings = (int)(targetfixingrate * nbinintvars) + 1;
 
   /* don't continue if number of discrete variables is too small to reach target fixing rate */
   if( nbinintvars <= ntargetfixings )
      return SCIP_OKAY;
 
   *result = SCIP_DIDNOTFIND;
 
   /* copy variables into a buffer array */
   SCIP_CALL( SCIPduplicateBufferArray(scip, &varscpy, vars, nbinintvars) );
 
   /* partially perturb the array until the number of target fixings is reached */
   for( i = 0; *nfixings < ntargetfixings && i < nbinintvars; ++i )
   {
      int randint = SCIPrandomGetInt(rng, i, nbinintvars - 1);
      assert(randint < nbinintvars);
 
      if( randint > i )
      {
         SCIPswapPointers((void**)&varscpy[i], (void**)&varscpy[randint]);
      }
      /* copy the selected variables and their solution values into the buffer */
      tryAdd2variableBuffer(scip, varscpy[i], SCIPgetSolVal(scip, incumbentsol, varscpy[i]), varbuf, valbuf, nfixings, TRUE);
   }
 
   assert(i == nbinintvars || *nfixings == ntargetfixings);
 
   /* Not reaching the number of target fixings means that there is a significant fraction (at least 1 - targetfixingrate)
    * of variables for which the incumbent solution value does not lie within the global bounds anymore. This is a nonsuccess
    * for the neighborhood (additional fixings are not possible), which is okay because the incumbent solution is
    * significantly outdated
    */
   if( *nfixings == ntargetfixings )
      *result = SCIP_SUCCESS;
 
   /* free the buffer array */
   SCIPfreeBufferArray(scip, &varscpy);
 
   return SCIP_OKAY;
}
 
/** add local branching constraint */
static
SCIP_RETCODE addLocalBranchingConstraint(
   SCIP*                 sourcescip,         /**< source SCIP data structure */
   SCIP*                 targetscip,         /**< target SCIP data structure */
   SCIP_VAR**            subvars,            /**< array of sub SCIP variables in same order as source SCIP variables */
   int                   distance,           /**< right hand side of the local branching constraint */
   SCIP_Bool*            success,            /**< pointer to store of a local branching constraint has been successfully added */
   int*                  naddedconss         /**< pointer to increase the number of added constraints */
   )
{
   int nbinvars;
   int i;
   SCIP_SOL* referencesol;
   SCIP_CONS* localbranchcons;
   SCIP_VAR** vars;
   SCIP_Real* consvals;
   SCIP_Real rhs;
 
   assert(sourcescip != NULL);
   assert(*success == FALSE);
 
   nbinvars = SCIPgetNBinVars(sourcescip);
   vars = SCIPgetVars(sourcescip);
 
   if( nbinvars <= 3 )
      return SCIP_OKAY;
 
   referencesol = SCIPgetBestSol(sourcescip);
   if( referencesol == NULL )
      return SCIP_OKAY;
 
   rhs = (SCIP_Real)distance;
   rhs = MAX(rhs, 2.0);
 
   SCIP_CALL( SCIPallocBufferArray(sourcescip, &consvals, nbinvars) );
 
   /* loop over binary variables and fill the local branching constraint */
   for( i = 0; i < nbinvars; ++i )
   {
      /* skip variables that are not present in sub-SCIP */
      if( subvars[i] == NULL )
         continue;
 
      if( SCIPisEQ(sourcescip, SCIPgetSolVal(sourcescip, referencesol, vars[i]), 0.0) )
         consvals[i] = 1.0;
      else
      {
         consvals[i] = -1.0;
         rhs -= 1.0;
      }
   }
 
   /* create the local branching constraint in the target scip */
   SCIP_CALL( SCIPcreateConsBasicLinear(targetscip, &localbranchcons, "localbranch", nbinvars, subvars, consvals, -SCIPinfinity(sourcescip), rhs) );
   SCIP_CALL( SCIPaddCons(targetscip, localbranchcons) );
   SCIP_CALL( SCIPreleaseCons(targetscip, &localbranchcons) );
 
   *naddedconss = 1;
   *success = TRUE;
 
   SCIPfreeBufferArray(sourcescip, &consvals);
 
   return SCIP_OKAY;
}
 
/** callback for local branching subproblem changes */
static
DECL_CHANGESUBSCIP(changeSubscipLocalbranching)
{  /*lint --e{715}*/
 
   SCIP_CALL( addLocalBranchingConstraint(sourcescip, targetscip, subvars, (int)(0.2 * SCIPgetNBinVars(sourcescip)), success, naddedconss) );
 
   return SCIP_OKAY;
}
 
/** callback for proximity subproblem changes */
static
DECL_CHANGESUBSCIP(changeSubscipProximity)
{  /*lint --e{715}*/
   SCIP_SOL* referencesol;
   SCIP_VAR** vars;
   int nbinvars;
   int nintvars;
   int nvars;
   int i;
 
   SCIP_CALL( SCIPgetVarsData(sourcescip, &vars, &nvars, &nbinvars, &nintvars, NULL, NULL) );
 
   if( nbinvars == 0 )
      return SCIP_OKAY;
 
   referencesol = SCIPgetBestSol(sourcescip);
   if( referencesol == NULL )
      return SCIP_OKAY;
 
   /* loop over binary variables, set objective coefficients based on reference solution in a local branching fashion */
   for( i = 0; i < nbinvars; ++i )
   {
      SCIP_Real newobj;
 
      /* skip variables not present in sub-SCIP */
      if( subvars[i] == NULL )
         continue;
 
      if( SCIPgetSolVal(sourcescip, referencesol, vars[i]) < 0.5 )
         newobj = -1.0;
      else
         newobj = 1.0;
      SCIP_CALL( SCIPchgVarObj(targetscip, subvars[i], newobj) );
   }
 
   /* loop over the remaining variables and change their objective coefficients to 0 */
   for( ; i < nvars; ++i )
   {
      /* skip variables not present in sub-SCIP */
      if( subvars[i] == NULL )
         continue;
 
      SCIP_CALL( SCIPchgVarObj(targetscip, subvars[i], 0.0) );
   }
 
   *nchgobjs = nvars;
   *success = TRUE;
 
   return SCIP_OKAY;
}
 
/** callback for zeroobjective subproblem changes */
static
DECL_CHANGESUBSCIP(changeSubscipZeroobjective)
{  /*lint --e{715}*/
   SCIP_CONSHDLR* conshdlrnl;
   SCIP_VAR** vars;
   int nvars;
   int i;
 
   assert(*success == FALSE);
 
   SCIP_CALL( SCIPgetVarsData(sourcescip, &vars, &nvars, NULL, NULL, NULL, NULL) );
 
   /* do not run if no objective variables are present */
   if( SCIPgetNObjVars(sourcescip) == 0 )
      return SCIP_OKAY;
 
   /* zeroobj may trigger fixing objvar in nonlinear constraint to infinity,
    * which expr_var.c:simplify cannot handle at the moment; also #3273
    */
   conshdlrnl = SCIPfindConshdlr(sourcescip, "nonlinear");
   if( conshdlrnl != NULL && SCIPconshdlrGetNActiveConss(conshdlrnl) > 0 )
      return SCIP_OKAY;
 
   /* loop over the variables and change their objective coefficients to 0 */
   for( i = 0; i < nvars; ++i )
   {
      /* skip variables not present in sub-SCIP */
      if( subvars[i] == NULL )
         continue;
 
      SCIP_CALL( SCIPchgVarObj(targetscip, subvars[i], 0.0) );
   }
 
   *nchgobjs = nvars;
   *success = TRUE;
 
   return SCIP_OKAY;
}
 
/** compute tightened bounds for integer variables depending on how much the LP and the incumbent solution values differ */
static
void computeIntegerVariableBoundsDins(
   SCIP*                 scip,               /**< SCIP data structure of the original problem */
   SCIP_VAR*             var,                /**< the variable for which bounds should be computed */
   SCIP_Real*            lbptr,              /**< pointer to store the lower bound in the DINS sub-SCIP */
   SCIP_Real*            ubptr               /**< pointer to store the upper bound in the DINS sub-SCIP */
   )
{
   SCIP_Real mipsol;
   SCIP_Real lpsol;
 
   SCIP_Real lbglobal;
   SCIP_Real ubglobal;
   SCIP_SOL* bestsol;
 
   /* get the bounds for each variable */
   lbglobal = SCIPvarGetLbGlobal(var);
   ubglobal = SCIPvarGetUbGlobal(var);
 
   assert(SCIPvarGetType(var) == SCIP_VARTYPE_INTEGER);
   /* get the current LP solution for each variable */
   lpsol = SCIPvarGetLPSol(var);
 
   /* get the current MIP solution for each variable */
   bestsol = SCIPgetBestSol(scip);
   mipsol = SCIPgetSolVal(scip, bestsol, var);
 
   /* if the solution values differ by 0.5 or more, the variable is rebounded, otherwise it is just copied */
   if( REALABS(lpsol - mipsol) >= 0.5 )
   {
      SCIP_Real range;
 
      *lbptr = lbglobal;
      *ubptr = ubglobal;
 
      /* create an equally sized range around lpsol for general integers: bounds are lpsol +- (mipsol-lpsol) */
      range = 2 * lpsol - mipsol;
 
      if( mipsol >= lpsol )
      {
         range = SCIPfeasCeil(scip, range);
         *lbptr = MAX(*lbptr, range);
 
         /* when the bound new upper bound is equal to the current MIP solution, we set both bounds to the integral bound (without eps) */
         if( SCIPisFeasEQ(scip, mipsol, *lbptr) )
            *ubptr = *lbptr;
         else
            *ubptr = mipsol;
      }
      else
      {
         range = SCIPfeasFloor(scip, range);
         *ubptr = MIN(*ubptr, range);
 
         /* when the bound new upper bound is equal to the current MIP solution, we set both bounds to the integral bound (without eps) */
         if( SCIPisFeasEQ(scip, mipsol, *ubptr) )
            *lbptr = *ubptr;
         else
            *lbptr = mipsol;
      }
 
      /* the global domain of variables might have been reduced since incumbent was found: adjust lb and ub accordingly */
      *lbptr = MAX(*lbptr, lbglobal);
      *ubptr = MIN(*ubptr, ubglobal);
   }
   else
   {
      /* the global domain of variables might have been reduced since incumbent was found: adjust it accordingly */
      *lbptr = MAX(mipsol, lbglobal);
      *ubptr = MIN(mipsol, ubglobal);
   }
}
 
/** callback to collect variable fixings of DINS */
static
DECL_VARFIXINGS(varFixingsDins)
{
   DATA_DINS* data;
   SCIP_SOL* rootlpsol;
   SCIP_SOL** sols;
   int nsols;
   int nmipsols;
   int nbinvars;
   int nintvars;
   SCIP_VAR** vars;
   int v;
 
   data = neighborhood->data.dins;
   assert(data != NULL);
   nmipsols = SCIPgetNSols(scip);
   nmipsols = MIN(nmipsols, data->npoolsols);
 
   *result = SCIP_DELAYED;
 
   if( SCIPgetLPSolstat(scip) != SCIP_LPSOLSTAT_OPTIMAL )
      return SCIP_OKAY;
 
   *result = SCIP_DIDNOTRUN;
 
   if( nmipsols == 0 )
      return SCIP_OKAY;
 
   SCIP_CALL( SCIPgetVarsData(scip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
 
   if( nbinvars + nintvars == 0 )
      return SCIP_OKAY;
 
   SCIP_CALL( SCIPcreateSol(scip, &rootlpsol, NULL) );
 
   /* save root solution LP values in solution */
   for( v = 0; v < nbinvars + nintvars; ++v )
   {
      SCIP_CALL( SCIPsetSolVal(scip, rootlpsol, vars[v], SCIPvarGetRootSol(vars[v])) );
   }
 
   /* add the node and the root LP solution */
   nsols = nmipsols + 2;
 
   SCIP_CALL( SCIPallocBufferArray(scip, &sols, nsols) );
   sols[0] = NULL; /* node LP solution */
   sols[1] = rootlpsol;
 
   /* copy the remaining MIP solutions after the LP solutions */
   BMScopyMemoryArray(&sols[2], SCIPgetSols(scip), nmipsols); /*lint !e866*/
 
   /* 1. Binary variables are fixed if their values agree in all the solutions */
   if( nbinvars > 0 )
   {
      SCIP_CALL( fixMatchingSolutionValues(scip, sols, nsols, vars, nbinvars, varbuf, valbuf, nfixings) );
   }
 
   /* 2. Integer variables are fixed if they have a very low distance between the incumbent and the root LP solution */
   for( v = nbinvars; v < nintvars; ++v )
   {
      SCIP_Real lb;
      SCIP_Real ub;
      computeIntegerVariableBoundsDins(scip, vars[v], &lb, &ub);
 
      if( ub - lb < 0.5 )
      {
         assert(SCIPisFeasIntegral(scip, lb));
         tryAdd2variableBuffer(scip, vars[v], lb, varbuf, valbuf, nfixings, TRUE);
      }
   }
 
   *result = SCIP_SUCCESS;
 
   SCIPfreeBufferArray(scip, &sols);
 
   SCIP_CALL( SCIPfreeSol(scip, &rootlpsol) );
 
   return SCIP_OKAY;
}
 
/** callback for DINS subproblem changes */
static
DECL_CHANGESUBSCIP(changeSubscipDins)
{  /*lint --e{715}*/
   SCIP_VAR** vars;
   int nintvars;
   int nbinvars;
   int v;
 
   SCIP_CALL( SCIPgetVarsData(sourcescip, &vars, NULL, &nbinvars, &nintvars, NULL, NULL) );
 
   /* 1. loop over integer variables and tighten the bounds */
   for( v = nbinvars; v < nintvars; ++v )
   {
      SCIP_Real lb;
      SCIP_Real ub;
 
      /* skip variables not present in sub-SCIP */
      if( subvars[v] == NULL )
         continue;
 
      computeIntegerVariableBoundsDins(sourcescip, vars[v], &lb, &ub);
 
      SCIP_CALL( SCIPchgVarLbGlobal(targetscip, subvars[v], lb) );
      SCIP_CALL( SCIPchgVarUbGlobal(targetscip, subvars[v], ub) );
      ++(*ndomchgs);
   }
 
   /* 2. add local branching constraint for binary variables */
   SCIP_CALL( addLocalBranchingConstraint(sourcescip, targetscip, subvars, (int)(0.1 * SCIPgetNBinVars(sourcescip)), success, naddedconss) );
 
   *success = TRUE;
 
   return SCIP_OKAY;
}
 
/** deinitialization callback for DINS before SCIP is freed */
static
DECL_NHFREE(nhFreeDins)
{
   assert(neighborhood->data.dins != NULL);
 
   SCIPfreeBlockMemory(scip, &neighborhood->data.dins);
 
   return SCIP_OKAY;
}
 
/** deinitialization callback for trustregion before SCIP is freed */
static
DECL_NHFREE(nhFreeTrustregion)
{
   assert(neighborhood->data.trustregion != NULL);
 
   SCIPfreeBlockMemory(scip, &neighborhood->data.trustregion);
 
   return SCIP_OKAY;
}
 
/** add trust region neighborhood constraint and auxiliary objective variable */
static
DECL_CHANGESUBSCIP(changeSubscipTrustregion)
{  /*lint --e{715}*/
   DATA_TRUSTREGION* data;
 
   data = neighborhood->data.trustregion;
 
   /* adding the neighborhood constraint for the trust region heuristic */
   SCIP_CALL( SCIPaddTrustregionNeighborhoodConstraint(sourcescip, targetscip, subvars, data->violpenalty) );
 
   /* incrementing the change in objective since an additional variable is added to the objective to penalize the
    * violation of the trust region.
    */
   ++(*nchgobjs);
 
   return SCIP_OKAY;
}
 
/** callback that returns the incumbent solution as a reference point */
static
DECL_NHREFSOL(nhRefsolIncumbent)
{  /*lint --e{715}*/
   assert(scip != NULL);
 
   if( SCIPgetBestSol(scip) != NULL )
   {
      *result = SCIP_SUCCESS;
      *solptr = SCIPgetBestSol(scip);
   }
   else
   {
      *result = SCIP_DIDNOTFIND;
   }
 
   return SCIP_OKAY;
}
 
 
/** callback function that deactivates a neighborhood on problems with no discrete variables */
static
DECL_NHDEACTIVATE(nhDeactivateDiscreteVars)
{ /*lint --e{715}*/
   assert(scip != NULL);
   assert(deactivate != NULL);
 
   /* deactivate if no discrete variables are present */
   *deactivate = (SCIPgetNBinVars(scip) + SCIPgetNIntVars(scip) == 0);
 
   return SCIP_OKAY;
}
 
/** callback function that deactivates a neighborhood on problems with no binary variables */
static
DECL_NHDEACTIVATE(nhDeactivateBinVars)
{ /*lint --e{715}*/
   assert(scip != NULL);
   assert(deactivate != NULL);
 
   /* deactivate if no discrete variables are present */
   *deactivate = (SCIPgetNBinVars(scip) == 0);
 
   return SCIP_OKAY;
}
 
/** callback function that deactivates a neighborhood on problems with no objective variables */
static
DECL_NHDEACTIVATE(nhDeactivateObjVars)
{ /*lint --e{715}*/
   assert(scip != NULL);
   assert(deactivate != NULL);
 
   /* deactivate if no discrete variables are present */
   *deactivate = (SCIPgetNObjVars(scip) == 0);
 
   return SCIP_OKAY;
}
 
 
/** include all neighborhoods */
static
SCIP_RETCODE includeNeighborhoods(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_HEURDATA*        heurdata            /**< heuristic data of the scheduler heuristic */
   )
{
   NH* rens;
   NH* rins;
   NH* mutation;
   NH* localbranching;
   NH* crossover;
   NH* proximity;
   NH* zeroobjective;
   NH* dins;
   NH* trustregion;
 
   heurdata->nneighborhoods = 0;
 
   /* include the RENS neighborhood */
   SCIP_CALL( schedulerIncludeNeighborhood(scip, heurdata, &rens, "rens",
         DEFAULT_MINFIXINGRATE_RENS, DEFAULT_MAXFIXINGRATE_RENS, DEFAULT_ACTIVE_RENS, DEFAULT_PRIORITY_RENS,
         varFixingsRens, changeSubscipRens, NULL, NULL, NULL, NULL, nhDeactivateDiscreteVars) );
 
   /* include the RINS neighborhood */
   SCIP_CALL( schedulerIncludeNeighborhood(scip, heurdata, &rins, "rins",
         DEFAULT_MINFIXINGRATE_RINS, DEFAULT_MAXFIXINGRATE_RINS, DEFAULT_ACTIVE_RINS, DEFAULT_PRIORITY_RINS,
         varFixingsRins, NULL, NULL, NULL, NULL, nhRefsolIncumbent, nhDeactivateDiscreteVars) );
 
   /* include the mutation neighborhood */
   SCIP_CALL( schedulerIncludeNeighborhood(scip, heurdata, &mutation, "mutation",
         DEFAULT_MINFIXINGRATE_MUTATION, DEFAULT_MAXFIXINGRATE_MUTATION, DEFAULT_ACTIVE_MUTATION, DEFAULT_PRIORITY_MUTATION,
         varFixingsMutation, NULL, nhInitMutation, nhExitMutation, NULL, nhRefsolIncumbent, nhDeactivateDiscreteVars) );
 
   /* include the local branching neighborhood */
   SCIP_CALL( schedulerIncludeNeighborhood(scip, heurdata, &localbranching, "localbranching",
         DEFAULT_MINFIXINGRATE_LOCALBRANCHING, DEFAULT_MAXFIXINGRATE_LOCALBRANCHING, DEFAULT_ACTIVE_LOCALBRANCHING, DEFAULT_PRIORITY_LOCALBRANCHING,
         NULL, changeSubscipLocalbranching, NULL, NULL, NULL, nhRefsolIncumbent, nhDeactivateBinVars) );
 
   /* include the crossover neighborhood */
   SCIP_CALL( schedulerIncludeNeighborhood(scip, heurdata, &crossover, "crossover",
         DEFAULT_MINFIXINGRATE_CROSSOVER, DEFAULT_MAXFIXINGRATE_CROSSOVER, DEFAULT_ACTIVE_CROSSOVER, DEFAULT_PRIORITY_CROSSOVER,
         varFixingsCrossover, NULL,
         nhInitCrossover, nhExitCrossover, nhFreeCrossover, nhRefsolCrossover, nhDeactivateDiscreteVars) );
 
   /* allocate data for crossover to include the parameter */
   SCIP_CALL( SCIPallocBlockMemory(scip, &crossover->data.crossover) );
   crossover->data.crossover->rng = NULL;
 
   /* add crossover neighborhood parameters */
   SCIP_CALL( SCIPaddIntParam(scip, "heuristics/scheduler/crossover/nsols", "the number of solutions that crossover should combine",
         &crossover->data.crossover->nsols, TRUE, DEFAULT_NSOLS_CROSSOVER, 2, 10, NULL, NULL) );
 
   /* include the Proximity neighborhood */
   SCIP_CALL( schedulerIncludeNeighborhood(scip, heurdata, &proximity, "proximity",
         DEFAULT_MINFIXINGRATE_PROXIMITY, DEFAULT_MAXFIXINGRATE_PROXIMITY, DEFAULT_ACTIVE_PROXIMITY, DEFAULT_PRIORITY_PROXIMITY,
         NULL, changeSubscipProximity, NULL, NULL, NULL, nhRefsolIncumbent, nhDeactivateBinVars) );
 
   /* include the Zeroobjective neighborhood */
   SCIP_CALL( schedulerIncludeNeighborhood(scip, heurdata, &zeroobjective, "zeroobjective",
         DEFAULT_MINFIXINGRATE_ZEROOBJECTIVE, DEFAULT_MAXFIXINGRATE_ZEROOBJECTIVE, DEFAULT_ACTIVE_ZEROOBJECTIVE, DEFAULT_PRIORITY_ZEROOBJECTIVE,
         NULL, changeSubscipZeroobjective, NULL, NULL, NULL, nhRefsolIncumbent, nhDeactivateObjVars) );
 
   /* include the DINS neighborhood */
   SCIP_CALL( schedulerIncludeNeighborhood(scip, heurdata, &dins, "dins",
         DEFAULT_MINFIXINGRATE_DINS, DEFAULT_MAXFIXINGRATE_DINS, DEFAULT_ACTIVE_DINS, DEFAULT_PRIORITY_DINS,
         varFixingsDins, changeSubscipDins, NULL, NULL, nhFreeDins, nhRefsolIncumbent, nhDeactivateBinVars) );
 
   /* allocate data for DINS to include the parameter */
   SCIP_CALL( SCIPallocBlockMemory(scip, &dins->data.dins) );
 
   /* add DINS neighborhood parameters */
   SCIP_CALL( SCIPaddIntParam(scip, "heuristics/scheduler/dins/npoolsols",
         "number of pool solutions where binary solution values must agree",
         &dins->data.dins->npoolsols, TRUE, DEFAULT_NPOOLSOLS_DINS, 1, 100, NULL, NULL) );
 
   /* include the trustregion neighborhood */
   SCIP_CALL( schedulerIncludeNeighborhood(scip, heurdata, &trustregion, "trustregion",
         DEFAULT_MINFIXINGRATE_TRUSTREGION, DEFAULT_MAXFIXINGRATE_TRUSTREGION, DEFAULT_ACTIVE_TRUSTREGION, DEFAULT_PRIORITY_TRUSTREGION,
         NULL, changeSubscipTrustregion, NULL, NULL, nhFreeTrustregion, nhRefsolIncumbent, nhDeactivateBinVars) );
 
   /* allocate data for trustregion to include the parameter */
   SCIP_CALL( SCIPallocBlockMemory(scip, &trustregion->data.trustregion) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/trustregion/violpenalty",
         "the penalty for each change in the binary variables from the candidate solution",
         &trustregion->data.trustregion->violpenalty, FALSE, DEFAULT_VIOLPENALTY_TRUSTREGION, 0.0, SCIP_REAL_MAX, NULL, NULL) );
 
   return SCIP_OKAY;
}
 
/** initialization method of primal heuristic (called after problem was transformed) */
static
SCIP_DECL_HEURINIT(heurInitScheduler)
{  /*lint --e{715}*/
   SCIP_HEURDATA* heurdata;
   int i;
 
   assert(scip != NULL);
   assert(heur != NULL);
 
   heurdata = SCIPheurGetData(heur);
   assert(heurdata != NULL);
 
   /* reactivate all neighborhoods if a new problem is read in */
   heurdata->nactiveneighborhoods = heurdata->nneighborhoods;
 
   /* initialize neighborhoods for new problem */
   for( i = 0; i < heurdata->nneighborhoods; ++i )
   {
      NH* neighborhood = heurdata->neighborhoods[i];
 
      SCIP_CALL( neighborhoodInit(scip, neighborhood) );
 
      SCIP_CALL( resetFixingRate(scip, &neighborhood->fixingrate) );
 
      SCIP_CALL( heurStatsReset(scip, &neighborhood->stats, FALSE) );
   }
 
   /* we clear the list of collected diving heuristics to ensure reproducability and consistent state across multiple runs
    * within the same SCIP data structure */
   /* note: diving heuristics data will be initialized when executing scheduler */
   if( heurdata->divingheurs != NULL )
   {
      SCIPfreeBlockMemoryArray(scip, &heurdata->divingheurs, heurdata->divingheurssize);
      assert(heurdata->divingheurs == NULL);
   }
 
   /* create working solution */
   SCIP_CALL( SCIPcreateSol(scip, &heurdata->sol, heur) );
 
   return SCIP_OKAY;
}
 
 
/** solving process initialization method of primal heuristic (called when branch and bound process is about to begin) */
static
SCIP_DECL_HEURINITSOL(heurInitsolScheduler)
{  /*lint --e{715}*/
   SCIP_HEURDATA* heurdata;
   int i;
   SCIP_Real* priorities;
   unsigned int initseed;
 
   assert(scip != NULL);
   assert(heur != NULL);
 
   heurdata = SCIPheurGetData(heur);
   assert(heurdata != NULL);
   heurdata->nactiveneighborhoods = heurdata->nneighborhoods;
 
   SCIP_CALL( SCIPallocBufferArray(scip, &priorities, heurdata->ndiving + heurdata->nactiveneighborhoods) );
 
   /* init neighborhoods for new problem by resetting their statistics and fixing rate */
   for( i = heurdata->nneighborhoods - 1; i >= 0; --i )
   {
      NH* neighborhood = heurdata->neighborhoods[i];
      SCIP_Bool deactivate;
 
      SCIP_CALL( neighborhood->nhdeactivate(scip, &deactivate) );
 
      /* disable inactive neighborhoods */
      if( deactivate || ! neighborhood->active )
      {
         if( heurdata->nactiveneighborhoods - 1 > i )
         {
            assert(heurdata->neighborhoods[heurdata->nactiveneighborhoods - 1]->active);
            SCIPswapPointers((void **)&heurdata->neighborhoods[i], (void **)&heurdata->neighborhoods[heurdata->nactiveneighborhoods - 1]);
         }
         heurdata->nactiveneighborhoods--;
      }
   }
 
   /* if diving is already initialized (only happens after all diving heuristics are initialized),
    * take the proper priorities. Otherwise, set all priorities to 1.0 */
   if( heurdata->divingheurs != NULL )
   {
      /* collect diving heuristic priorities */
      for( i = 0; i < heurdata->ndiving; ++i )
         priorities[i] = heurdata->divingheurs[i]->priority;
 
      /* collect neighborhood priorities */
      for( i = 0; i < heurdata->nactiveneighborhoods; ++i )
         priorities[i + heurdata->ndiving] = heurdata->neighborhoods[i]->priority;
   }
   else
   {
      for( i = 0; i < heurdata->ndiving + heurdata->nactiveneighborhoods; ++i )
         priorities[i] = 1.0;
   }
 
   initseed = (unsigned int)(heurdata->seed + SCIPgetNVars(scip));
 
   /* active neighborhoods might change between init calls, reset functionality must take this into account */
   if( heurdata->bandit != NULL && SCIPbanditGetNActions(heurdata->bandit) != heurdata->ndiving + heurdata->nactiveneighborhoods )
   {
      SCIP_CALL( SCIPfreeBandit(scip, &heurdata->bandit) );
      heurdata->bandit = NULL;
 
      /* since the number of active heursitics has changed, we have to update
       * how heuristics are sorted by priority, if we already initialized the data */
      if( heurdata->divingheurs != NULL )
      {
         SCIP_Real* initpriorities;
         int nheurs;
 
         nheurs = heurdata->nactiveneighborhoods + heurdata->ndiving;
         SCIP_CALL( SCIPallocBufferArray(scip, &initpriorities, nheurs) );
         heurdata->counter = 0;
 
         for( i = 0; i < nheurs; ++i )
         {
            heurdata->sortedindices[i] = i;
 
            if( i < heurdata->ndiving )
               initpriorities[i] = (SCIP_Real)-heurdata->divingheurs[i]->rootnodepriority;
            else
               initpriorities[i] = (SCIP_Real)-heurdata->neighborhoods[i - heurdata->ndiving]->rootnodepriority;
         }
 
         SCIPsortRealInt(initpriorities, heurdata->sortedindices, nheurs);
 
         SCIPfreeBufferArray(scip, &initpriorities);
      }
   }
 
   if( heurdata->nactiveneighborhoods + heurdata->ndiving > 0 )
   {  /* create or reset bandit algorithm */
      if( heurdata->bandit == NULL )
      {
         SCIP_CALL( createBandit(scip, heurdata, priorities, initseed) );
         resetTargetNodeLimit(heurdata);
      }
      else if( heurdata->resetweights )
      {
         SCIP_CALL( SCIPresetBandit(scip, heurdata->bandit, priorities, initseed) );
         resetTargetNodeLimit(heurdata);
      }
   }
 
   /* TODO: maybe do something for diving as well here? */
   heurdata->usednodes = 0;
   heurdata->ninitneighborhoods = heurdata->nactiveneighborhoods;
 
   heurdata->lastcallsol = NULL;
   heurdata->firstcallthissol = 0;
 
   resetCurrentNeighborhood(heurdata);
 
   SCIPfreeBufferArray(scip, &priorities);
 
   return SCIP_OKAY;
}
 
 
/** deinitialization method of primal heuristic (called before transformed problem is freed) */
static
SCIP_DECL_HEUREXIT(heurExitScheduler)
{  /*lint --e{715}*/
   SCIP_HEURDATA* heurdata;
   int i;
 
   assert(scip != NULL);
   assert(heur != NULL);
 
   heurdata = SCIPheurGetData(heur);
   assert(heurdata != NULL);
 
   /* free neighborhood specific data */
   for( i = 0; i < heurdata->nneighborhoods; ++i )
   {
      NH* neighborhood = heurdata->neighborhoods[i];
 
      SCIP_CALL( neighborhoodExit(scip, neighborhood) );
   }
 
   /* free working solution */
   SCIP_CALL( SCIPfreeSol(scip, &heurdata->sol) );
 
   return SCIP_OKAY;
}
 
/** destructor of primal heuristic to free user data (called when SCIP is exiting) */
static
SCIP_DECL_HEURFREE(heurFreeScheduler)
{  /*lint --e{715}*/
   SCIP_HEURDATA* heurdata;
   int i;
 
   assert(scip != NULL);
   assert(heur != NULL);
 
   heurdata = SCIPheurGetData(heur);
   assert(heurdata != NULL);
 
   /* bandits are only initialized if a problem has been read */
   if( heurdata->bandit != NULL )
   {
      SCIP_CALL( SCIPfreeBandit(scip, &heurdata->bandit) );
   }
 
   /* free diving heuristics */
   if( heurdata->divingheurs != NULL )
   {
      int j;
 
      for( j = 0; j < heurdata->ndiving; ++j )
      {
         SCIP_CALL( schedulerFreeDivingHeur(scip, &(heurdata->divingheurs[j])) );
      }
 
      SCIPfreeBlockMemoryArray(scip, &heurdata->divingheurs, heurdata->divingheurssize);
 
      if( heurdata->defaultroot )
         SCIPfreeBlockMemoryArray(scip, &heurdata->sortedindices, heurdata->ndiving + heurdata->nneighborhoods);
   }
 
   /* free neighborhoods */
   for( i = 0; i < heurdata->nneighborhoods; ++i )
   {
      SCIP_CALL( schedulerFreeNeighborhood(scip, &(heurdata->neighborhoods[i])) );
   }
 
   SCIPfreeBlockMemoryArray(scip, &heurdata->neighborhoods, NNEIGHBORHOODS);
 
   SCIPfreeBlockMemory(scip, &heurdata);
 
   return SCIP_OKAY;
}
 
/** output method of statistics table to output file stream 'file' */
static
SCIP_DECL_TABLEOUTPUT(tableOutputNeighborhood)
{ /*lint --e{715}*/
   SCIP_HEURDATA* heurdata;
 
   assert(SCIPfindHeur(scip, HEUR_NAME) != NULL);
   heurdata = SCIPheurGetData(SCIPfindHeur(scip, HEUR_NAME));
   assert(heurdata != NULL);
 
   /* print neighborhood statistics */
   printNeighborhoodStatistics(scip, heurdata, file);
 
   /* print only diving statistics if scheduler got executed at least once (because we only then
    * initialize the diving heuristics)
    * Note: More Diving statistics will be printed in scip_solvingstats.c with all other stats about
    * diving since adaptive diving and the scheudler use the same diving context
    */
   if( heurdata->divingheurs != NULL )
      printDivingHeurStatistics(scip, heurdata, file);
 
   return SCIP_OKAY;
}
 
/*
 * primal heuristic specific interface methods
 */
 
/** creates the scheduler primal heuristic and includes it in SCIP */
SCIP_RETCODE SCIPincludeHeurScheduler(
   SCIP*                 scip                /**< SCIP data structure */
   )
{
   SCIP_HEURDATA* heurdata;
   SCIP_HEUR* heur;
 
   /* create primal heuristic data */
   heurdata = NULL;
   heur = NULL;
 
   SCIP_CALL( SCIPallocBlockMemory(scip, &heurdata) );
   BMSclearMemory(heurdata);
 
   /* TODO make this a user parameter? */
   heurdata->lplimfac = LPLIMFAC;
 
   heurdata->nskippedcalls = 0;
   heurdata->nfailedcalls = 0;
   heurdata->maxnconflicts = 0;
 
   /* allocate memory for LNS heuristics */
   SCIP_CALL( SCIPallocBlockMemoryArray(scip, &heurdata->neighborhoods, NNEIGHBORHOODS) );
 
   /* include primal heuristic */
   SCIP_CALL( SCIPincludeHeurBasic(scip, &heur,
         HEUR_NAME, HEUR_DESC, HEUR_DISPCHAR, HEUR_PRIORITY, HEUR_FREQ, HEUR_FREQOFS,
         HEUR_MAXDEPTH, HEUR_TIMING, HEUR_USESSUBSCIP, heurExecScheduler, heurdata) );
 
   assert(heur != NULL);
 
   /* include all neighborhoods */
   /* note: diving heuristics will be included when executing the scheduler heuristic for
    * the first time, because it relies on all heuristics being already added to SCIP
    */
   SCIP_CALL( includeNeighborhoods(scip, heurdata) );
 
   /* set non fundamental callbacks via setter functions */
   SCIP_CALL( SCIPsetHeurCopy(scip, heur, heurCopyScheduler) );
   SCIP_CALL( SCIPsetHeurFree(scip, heur, heurFreeScheduler) );
   SCIP_CALL( SCIPsetHeurInit(scip, heur, heurInitScheduler) );
   SCIP_CALL( SCIPsetHeurInitsol(scip, heur, heurInitsolScheduler) );
   SCIP_CALL( SCIPsetHeurExit(scip, heur, heurExitScheduler) );
 
   /* add scheduler primal heuristic parameters */
   SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/maxnodes",
         "maximum number of nodes to regard in the subproblem",
         &heurdata->maxnodes,  TRUE,DEFAULT_MAXNODES, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
 
   SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/nodesofs",
         "offset added to the nodes budget",
         &heurdata->nodesoffset, FALSE, DEFAULT_NODESOFFSET, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
 
   SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/minnodes",
         "minimum number of nodes required to start a sub-SCIP",
         &heurdata->minnodes, TRUE, DEFAULT_MINNODES, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
 
   SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/waitingnodes",
         "number of nodes since last incumbent solution that the heuristic should wait",
         &heurdata->waitingnodes, TRUE, DEFAULT_WAITINGNODES, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
 
   SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/initlnsnodelimit",
         "initial node limit for LNS heuristics",
         &heurdata->initlnsnodelimit, TRUE, DEFAULT_INITLNSNODELIMIT, 0, INT_MAX, NULL, NULL) );
 
   SCIP_CALL( SCIPaddLongintParam(scip, "heuristics/" HEUR_NAME "/initdivingnodelimit",
         "initial node limit for diving heuristics",
         &heurdata->initdivingnodelimit, TRUE, DEFAULT_INITDIVINGNODELIMIT, 0LL, SCIP_LONGINT_MAX, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/nodesquot",
         "fraction of nodes compared to the main SCIP for budget computation",
         &heurdata->nodesquot, FALSE, DEFAULT_NODESQUOT, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/nodesquotmin",
         "lower bound fraction of nodes compared to the main SCIP for budget computation",
         &heurdata->nodesquotmin, FALSE, DEFAULT_NODESQUOTMIN, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/nsolslim",
         "limit on the number of improving solutions in a sub-SCIP call",
         &heurdata->nsolslim, FALSE, DEFAULT_NSOLSLIM, -1, INT_MAX, NULL, NULL) );
 
   SCIP_CALL( SCIPaddCharParam(scip, "heuristics/" HEUR_NAME "/banditalgo",
         "the bandit algorithm: (u)pper confidence bounds, (e)xp.3, epsilon (g)reedy, exp.3-(i)x",
         &heurdata->banditalgo, TRUE, DEFAULT_BANDITALGO, "uegi", NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/gamma",
         "weight between uniform (gamma ~ 1) and weight driven (gamma ~ 0) probability distribution for exp3",
         &heurdata->exp3_gamma, TRUE, DEFAULT_GAMMA, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/beta",
         "reward offset between 0 and 1 at every observation for Exp.3",
         &heurdata->exp3_beta, TRUE, DEFAULT_BETA, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/alpha",
         "parameter to increase the confidence width in UCB",
         &heurdata->ucb_alpha, TRUE, DEFAULT_ALPHA, 0.0, 100.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/usedistances",
         "distances from fixed variables be used for variable prioritization",
         &heurdata->usedistances, TRUE, DEFAULT_USEDISTANCES, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/useredcost",
         "should reduced cost scores be used for variable prioritization?",
         &heurdata->useredcost, TRUE, DEFAULT_USEREDCOST, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/usepscost",
         "should pseudo cost scores be used for variable priorization?",
         &heurdata->usepscost, TRUE, DEFAULT_USEPSCOST, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/uselocalredcost",
         "should local reduced costs be used for generic (un)fixing?",
         &heurdata->uselocalredcost, TRUE, DEFAULT_USELOCALREDCOST, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/usesubscipheurs",
         "should the heuristic activate other sub-SCIP heuristics during its search?",
         &heurdata->usesubscipheurs, TRUE, DEFAULT_USESUBSCIPHEURS, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/targetnodefactor",
         "factor by which target node number is eventually increased",
         &heurdata->targetnodefactor, TRUE, DEFAULT_TARGETNODEFACTOR, 1.0, 1e+5, NULL, NULL) );
 
   SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/seed",
         "initial random seed for bandit algorithms and random decisions by neighborhoods",
         &heurdata->seed, FALSE, DEFAULT_SEED, 0, INT_MAX, NULL, NULL) );
 
   SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/maxcallssamesol",
         "number of allowed executions of the heuristic on the same incumbent solution (-1: no limit, 0: number of active neighborhoods)",
         &heurdata->maxcallssamesol, TRUE, DEFAULT_MAXCALLSSAMESOL, -1, 100, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/eps",
         "increase exploration in epsilon-greedy bandit algorithm",
         &heurdata->epsgreedy_eps, TRUE, DEFAULT_EPS, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/epsgreedy_usemod",
         "TRUE if modified version of the epsilon-greedy bandit algorithm should be used",
         &heurdata->epsgreedy_usemod, TRUE, TRUE, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/solrewardweight",
         "weight by how much finding a new incumbent is rewarded in reward function",
         &heurdata->solrewardweight, TRUE, DEFAULT_SOLREWARDWEIGHT, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/effortrewardweight",
         "weight by how much effort is rewarded in reward function",
         &heurdata->effortrewardweight, TRUE, DEFAULT_EFFORTREWARDWEIGHT, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/qualrewardweight",
         "weight by how much quality of a new incumbent is rewarded in reward function",
         &heurdata->qualrewardweight, TRUE, DEFAULT_QUALREWARDWEIGHT, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/conflictrewardweight",
         "weight by how much number of conflicts found by diving is rewarded in reward function",
         &heurdata->conflictrewardweight, TRUE, DEFAULT_CONFLICTREWARDWEIGHT, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/resetweights",
         "should the bandit algorithms be reset when a new problem is read?",
         &heurdata->resetweights, TRUE, DEFAULT_RESETWEIGHTS, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/subsciprandseeds",
         "should random seeds of sub-SCIPs be altered to increase diversification?",
         &heurdata->subsciprandseeds, TRUE, DEFAULT_SUBSCIPRANDSEEDS, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/copycuts",
         "should cutting planes be copied to the sub-SCIP?",
         &heurdata->copycuts, TRUE, DEFAULT_COPYCUTS, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/fixtol",
         "tolerance by which the fixing rate may be missed without generic fixing",
         &heurdata->fixtol, TRUE, DEFAULT_FIXTOL, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/unfixtol",
         "tolerance by which the fixing rate may be exceeded without generic unfixing",
         &heurdata->unfixtol, TRUE, DEFAULT_UNFIXTOL, 0.0, 1.0, NULL, NULL) );
 
   SCIP_CALL( SCIPaddRealParam(scip, "heuristics/" HEUR_NAME "/heurtimelimit",
         "time limit for a single heuristic run",
         &heurdata->heurtimelimit, TRUE, DEFAULT_HEURTIMELIMIT, 0.0, SCIP_REAL_MAX, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/initduringroot",
         "should the heuristic be executed multiple times during the root node?",
         &heurdata->initduringroot, TRUE, DEFAULT_INITDURINGROOT, NULL, NULL) );
 
   SCIP_CALL( SCIPaddBoolParam(scip, "heuristics/" HEUR_NAME "/defaultroot",
         "should the default priorities be used at the root node?",
         &heurdata->defaultroot, TRUE, TRUE, NULL, NULL) );
 
   SCIP_CALL( SCIPaddIntParam(scip, "heuristics/" HEUR_NAME "/nselections",
         "number of heuristics picked by the scheduler in one call (-1: number of controlled heuristics, 0: until new incumbent is found)",
         &heurdata->nselections, TRUE, DEFAULT_NSELECTIONS, -1, 100, NULL, NULL) );
 
   assert(SCIPfindTable(scip, TABLE_NAME_NEIGHBORHOOD) == NULL);
   SCIP_CALL( SCIPincludeTable(scip, TABLE_NAME_NEIGHBORHOOD, TABLE_DESC_NEIGHBORHOOD, TRUE,
         NULL, NULL, NULL, NULL, NULL, NULL, tableOutputNeighborhood,
         NULL, TABLE_POSITION_NEIGHBORHOOD, TABLE_EARLIEST_STAGE_NEIGHBORHOOD) );
 
   return SCIP_OKAY;
}