HeurFrats.h

Go to the documentation of this file.

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*                                                                           */
/*                  This file is part of the program and library             */
/*         SCIP --- Solving Constraint Integer Programs                      */
/*                                                                           */
/*  Copyright (c) 2002-2023 Zuse Institute Berlin (ZIB)                      */
/*                                                                           */
/*  Licensed under the Apache License, Version 2.0 (the "License");          */
/*  you may not use this file except in compliance with the License.         */
/*  You may obtain a copy of the License at                                  */
/*                                                                           */
/*      http://www.apache.org/licenses/LICENSE-2.0                           */
/*                                                                           */
/*  Unless required by applicable law or agreed to in writing, software      */
/*  distributed under the License is distributed on an "AS IS" BASIS,        */
/*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */
/*  See the License for the specific language governing permissions and      */
/*  limitations under the License.                                           */
/*                                                                           */
/*  You should have received a copy of the Apache-2.0 license                */
/*  along with SCIP; see the file LICENSE. If not visit scipopt.org.         */
/*                                                                           */
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/**@file   HeurFrats.h
 * @brief  fractional travelling salesman heuristic - Rounding heuristic for TSP
 * @author Timo Berthold
 */

/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/

#ifndef __HEURFRATS_H__
#define __HEURFRATS_H__


#include "objscip/objheur.h"
#include "GomoryHuTree.h"

namespace tsp
{

/** C++ rounding heuristic for TSP */
class HeurFrats : public scip::ObjHeur
{
   GRAPH*                graph;              /**< the underlying graph of the TSP */
   SCIP_SOL*             sol;                /**< current solution */

public:
   /** default constructor */
   HeurFrats(
      SCIP* scip
      )
      : ObjHeur(scip, "frats", "fractional travelling salesman: TSP rounding heuristic", 'T',-50000, 5, 0, -1,
         SCIP_HEURTIMING_AFTERLPNODE, FALSE),
      graph(NULL),
      sol(NULL)
   {
   }

   /** destructor */
   virtual ~HeurFrats()
   {
   } /*lint !e1540*/

   /** destructor of primal heuristic to free user data (called when SCIP is exiting) */
   virtual SCIP_DECL_HEURFREE(scip_free);

   /** initialization method of primal heuristic (called after problem was transformed) */
   virtual SCIP_DECL_HEURINIT(scip_init);

   /** deinitialization method of primal heuristic (called before transformed problem is freed) */
   virtual SCIP_DECL_HEUREXIT(scip_exit);

   /** solving process initialization method of primal heuristic (called when branch and bound process is about to begin)
    *
    *  This method is called when the presolving was finished and the branch and bound process is about to begin.
    *  The primal heuristic may use this call to initialize its branch and bound specific data.
    *
    */
   virtual SCIP_DECL_HEURINITSOL(scip_initsol);

   /** solving process deinitialization method of primal heuristic (called before branch and bound process data is freed)
    *
    *  This method is called before the branch and bound process is freed.
    *  The primal heuristic should use this call to clean up its branch and bound data.
    */
   virtual SCIP_DECL_HEUREXITSOL(scip_exitsol);

   /** execution method of primal heuristic
    *
    *  Searches for feasible primal solutions. The method is called in the node processing loop.
    *
    *  possible return values for *result:
    *  - SCIP_FOUNDSOL   : at least one feasible primal solution was found
    *  - SCIP_DIDNOTFIND : the heuristic searched, but did not find a feasible solution
    *  - SCIP_DIDNOTRUN  : the heuristic was skipped
    *  - SCIP_DELAYED    : the heuristic was skipped, but should be called again as soon as possible, disregarding
    *                      its frequency
    */
   virtual SCIP_DECL_HEUREXEC(scip_exec);

   /** clone method which will be used to copy a objective plugin */
   virtual SCIP_DECL_HEURCLONE(ObjCloneable* clone); /*lint !e665*/

   /** returns whether the objective plugin is copyable */
   virtual SCIP_DECL_HEURISCLONEABLE(iscloneable)
   {
      return TRUE;
   }
}; /*lint !e1712*/

}
#endif