/********************************************************
  Xpress-BCL C++ Example Problems
  ===============================

  file xbcutex.cxx
  ````````````````
  Simplified version of xbexpl1.cxx showing how 
  to define cuts with BCL.

  (c) 2008-2024 Fair Isaac Corporation
      author: S.Heipcke, 2005, rev. Mar. 2011
********************************************************/

#include <iostream> #include "xprb_cpp.h" #include "xprs.h" using namespace std; using namespace ::dashoptimization; #define NJ 4 /* Number of jobs */ #define NT 10 /* Time limit */ /**** DATA ****/ double DUR[] = {3,4,2,2}; /* Durations of jobs */ XPRBvar start[NJ]; /* Start times of jobs */ XPRBvar delta[NJ][NT]; /* Binaries for start times */ XPRBvar z; /* Maximum completion time (makespan) */ void jobsModel(XPRBprob &p);/* Basic model formulation */ void jobsSolve(XPRBprob &p);/* Solving and solution printing */ /***********************************************************************/ int XPRS_CC usrcme(XPRSprob oprob, void* vd) { XPRBcut ca[2]; int num; int i=0; XPRBprob *bprob; /* In terms of an example, we add a few additional constraints (without any relation to the original problem) at the second node of the MIP search tree. These constraints/cuts are applied at this node and all its child nodes. */ bprob = (XPRBprob*)vd; bprob->beginCB(oprob); XPRSgetintattrib(oprob, XPRS_NODES, &num); if(num == 2) { ca[0] = bprob->newCut(start[1]+2 <= start[0], 2); ca[1] = bprob->newCut(4*start[2] - 5,3*start[3] <= -17, 2); cout << "Adding constraints:" << endl; for(i=0;i<2;i++) ca[i].print(); if(bprob->addCuts(ca,2)) cout << "Problem with adding cuts." << endl; } bprob->endCB(); return 0; /* Call this function once per node */ } /*************************************************************************/ void jobsModel(XPRBprob &p) { XPRBexpr le; int j,t; /****VARIABLES****/ /* Create start time variables */ for(j=0;j<NJ;j++) start[j] = p.newVar("start");
 z = p.newVar("z",XPRB_PL,0,NT);  /* Declare the makespan variable */

 for(j=0;j<NJ;j++)              /* Declare binaries for each job  */
  for(t=0;t<(NT-DUR[j]+1);t++)
   delta[j][t] = p.newVar(XPRBnewname("delta%d%d",j+1,t+1),XPRB_BV);

/****CONSTRAINTS****/
 for(j=0;j<NJ;j++)              /* Calculate maximal completion time */
  p.newCtr("Makespan", start[j]+DUR[j] <= z);
  
 p.newCtr("Prec", start[0]+DUR[0] <= start[2]);
                                /* Precedence relation between jobs  */

 for(j=0;j<NJ;j++)              /* Linking start times and binaries  */ 
 { 
  le=0;
  for(t=0;t<(NT-DUR[j]+1);t++)  le += (t+1)*delta[j][t]; 
  p.newCtr(XPRBnewname("Link_%d",j+1), le == start[j]);
 } 
               
 for(j=0;j<NJ;j++)              /* One unique start time for each job  */
 { 
  le=0;
  for(t=0;t<(NT-DUR[j]+1);t++)  le += delta[j][t]; 
  p.newCtr(XPRBnewname("One_%d",j+1), le == 1);
 }      
              
/****OBJECTIVE****/
 p.setObj(p.newCtr("OBJ", z));  /* Define and set objective function */ 

/****BOUNDS****/
 for(j=0;j<NJ;j++) start[j].setUB(NT-DUR[j]+1); 
                                /* Upper bounds on start time variables */
} 

/*************************************************************************/

void jobsSolve(XPRBprob &p)
{ 
 int j,t,statmip; 
 XPRSprob oprob;

 oprob = p.getXPRSprob();
 XPRSsetintcontrol(oprob,XPRS_HEUREMPHASIS,0);
 XPRSsetintcontrol(oprob,XPRS_CUTSTRATEGY,0);
                             /* Switch heuristics and cut generation off:
                                otherwise this problem is solved in the
                                first node of the MIP search tree */

 p.setCutMode(1);                /* Enable the cut mode */
 XPRSsetcbcutmgr(oprob,usrcme,&p);

 p.setSense(XPRB_MINIM);
 p.mipOptimize("");              /* Solve the problem as MIP */
 statmip = p.getMIPStat();       /* Get the MIP problem status */    
              
 if((statmip == XPRB_MIP_SOLUTION) || (statmip == XPRB_MIP_OPTIMAL))
                                 /* An integer solution has been found */
 {  
  cout << "Objective: " << p.getObjVal() << endl; 
  for(j=0;j<NJ;j++) 
  {                              /* Print the solution for all start times */
   cout << start[j].getName() << ": " << start[j].getSol() << endl; 
   for(t=0;t<NT-DUR[j]+1;t++) 
    cout << delta[j][t].getName() << ": " << delta[j][t].getSol() << " ";
   cout << endl;
  }
 } 
}

/*************************************************************************/

int main(int argc, char **argv) 
{
  XPRBprob p("Jobs");         /* Initialize BCL and a new problem */ 
  jobsModel(p);               /* Basic problem definition */
  jobsSolve(p);               /* Solve and print solution */
  return 0;     
}