/******************************************************** BCL Example Problems ==================== file xbcontr2.c ``````````````` Contract allocation example. Combining BCL problem input with problem solving and callbacks in Xpress-Optimizer. (c) 2008 Fair Isaac Corporation author: S.Heipcke, Jan. 2000, rev. Mar. 2011 ********************************************************/ #include <stdio.h>
#include <stdlib.h>
#include "xprb.h"
#include "xprs.h"

#define District 6                  /* Number of districts */
#define Contract 10                 /* Number of contracts */

/**** DATA ****/
int OUTPUT[] = {50, 40, 10, 20, 70, 50};    /* Max. output per district */
int COST[]   = {50, 20, 25, 30, 45, 40};    /* Cost per district */
int VOLUME[]   = {20, 10, 30, 15, 20, 30, 10, 50, 10, 20};
                                    /* Volume of contracts */

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

void XPRS_CC printsolution(XPRSprob oprob, void *vp)
{
 int num,d,c;
 XPRBprob bprob;
 XPRBvar y;

 bprob = (XPRBprob)vp;
 XPRBbegincb(bprob, oprob);

 XPRSgetintattrib(oprob, XPRS_MIPSOLS, &num); /* Get number of the solution */

 XPRBsync(bprob, XPRB_XPRS_SOL);              /* Update BCL solution values */
 printf("Solution %d: Objective value: %g\n", num, XPRBgetobjval(bprob));
 for(d=0;d<District;d++) for(c=0;c<Contract;c++) y=XPRBgetbyname(bprob,>-1) && (XPRBgetsol(y) != 0))
    printf("%s: %g\n", XPRBgetvarname(y), XPRBgetsol(y));
  }

 XPRBendcb(bprob);
}

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

int main(int argc, char **argv)
{
 int d,c;
 XPRBctr c1,c2,cobj;
 XPRBvar x[District][Contract];    /* Variables indicating whether a project
                                      is chosen */
 XPRBvar y[District][Contract];    /* Quantities allocated to contractors */
 XPRBprob bprob;

 bprob=XPRBnewprob("Contr2");      /* Initialize a new problem in BCL */

/**** VARIABLES ****/
 for(d=0;d<District;d++)
  for(c=0;c<Contract;c++)
  {
   x[d][c] = XPRBnewvar(bprob,XPRB_BV,XPRBnewname("x_d%dc%d",d+1,c+1),0,1);
   y[d][c] =
     XPRBnewvar(bprob,XPRB_SC,XPRBnewname("q_d%dc%d",d+1,c+1),0,OUTPUT[d]);
   XPRBsetlim(y[d][c],5);
  }

/****OBJECTIVE****/
 cobj = XPRBnewctr(bprob,"OBJ",XPRB_N);  /* Define objective: total cost */
 for(d=0;d<District;d++)
  for(c=0;c<Contract;c++)
   XPRBaddterm(cobj,y[d][c],COST[d]);
 XPRBsetobj(bprob,cobj);                 /* Set objective function */

/**** CONSTRAINTS ****/
 for(c=0;c<Contract;c++)
 {
  c1=XPRBnewctr(bprob,"Size",XPRB_G);  /* Cover the required contract volume */
  c2=XPRBnewctr(bprob,"Min",XPRB_G);   /* At least 2 districts per contract */
  for(d=0;d<District;d++)
  {
   XPRBaddterm(c1,y[d][c],1);
   XPRBaddterm(c2,x[d][c],1);
  }
  XPRBaddterm(c1,NULL,VOLUME[c]);
  XPRBaddterm(c2,NULL,2);
 }

 for(d=0;d<District;d++)        /* Do not exceed max. output of any district */
 {
  c1=XPRBnewctr(bprob,"Output",XPRB_L);
  for(c=0;c<Contract;c++)
   XPRBaddterm(c1,y[d][c],1);
  XPRBaddterm(c1,NULL,OUTPUT[d]);
 }

 for(d=0;d<District;d++)        /* If a contract is allocated to a district,
                                   then at least 1 unit is allocated to it */
  for(c=0;c<Contract;c++)
   XPRBnewprec(bprob,"XY",x[d][c],0,y[d][c]);

/****SOLVING + OUTPUT****/
 XPRSsetcbintsol(XPRBgetXPRSprob(bprob), printsolution, bprob);
                                /* Define an integer solution callback */
 XPRBmipoptimize(bprob,"");     /* Solve the MIP problem */

 return 0;
}