/******************************************************** BCL Example Problems ==================== file xbcontr1.c ``````````````` Contract allocation example. Combining BCL problem input with problem solving in Xpress-Optimizer. (c) 2008 Fair Isaac Corporation author: S.Heipcke, Jan. 2000, rev. June 2010 ********************************************************/ #include <stdio.h>
#include <stdlib.h>
#include <string.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 */

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

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 */
 int i, ncol, len, stat, offset;
 double *sol, val;
 char *names;
 XPRSprob oprob;
 XPRBprob bprob;

 bprob=XPRBnewprob("Contr1");      /* 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****/
 XPRBloadmat(bprob);                   /* Load the matrix explicitely */
 oprob = XPRBgetXPRSprob(bprob);       /* Retrieve the Optimizer problem */
 XPRSchgobjsense(oprob, XPRS_OBJ_MINIMIZE);  /* Set sense to minimization */
 XPRSmipoptimize(oprob, "");           /* Solve the MIP problem */

 XPRSgetintattrib(oprob, XPRS_MIPSTATUS, &stat);  /* Get MIP status */
 if((stat==XPRS_MIP_SOLUTION) || (stat==XPRS_MIP_OPTIMAL)) 
                                /* Test whether an integer solution was found */
 {
  XPRSgetdblattrib(oprob, XPRS_MIPOBJVAL, &val);   
  printf("Objective: %g\n", val);
  XPRSgetintattrib(oprob, XPRS_ORIGINALCOLS, &ncol); 
  sol = (double *)malloc(ncol * sizeof(double));
  XPRSgetmipsol(oprob, sol, NULL);     /* Get the primal solution values */
  
  XPRSgetnamelist(oprob, 2, NULL, 0, &len, 0, ncol-1);    
                        /* Get number of bytes required for retrieving names */
  names = (char *)malloc(len*sizeof(char));
  XPRSgetnamelist(oprob, 2, names, len, NULL, 0, ncol-1); 
                                       /* Get the variable names */
  offset=0;
  for(i=0; i<ncol; i++) {              /* Print out the solution */
   if(sol[i]!=0)
    printf("%s: %g, ", names+offset, sol[i]);
   offset += strlen(names+offset)+1;
  }     
  printf("\n"); 
  free(names);
  free(sol); 
 }
  
 return 0;
}