/******************************************************** Xpress-BCL C++ Example Problems =============================== file xbcontr1.cxx ````````````````` Contract allocation example. Combining BCL problem input with problem solving in Xpress-Optimizer. (c) 2008-2024 Fair Isaac Corporation author: S.Heipcke, Jan. 2000, rev. Oct. 2010 ********************************************************/ #include <iostream>
#include <cstring>
#include "xprb_cpp.h"
#include "xprs.h"

using namespace std;
using namespace ::dashoptimization;

#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;
 XPRBexpr l1,l2,lobj;
 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 op;
 XPRBprob p("Contr1");                /* Initialize a new problem in BCL */
 
/**** VARIABLES ****/
 for(d=0;d<District;d++) for(c=0;c<Contract;c++) x[d][c]=p.newVar(XPRBnewname("x_d%dc%d",d+1,c+1),XPRB_BV); y[d][c]=p.newVar(XPRBnewname("q_d%dc%d",d+1,c+1),XPRB_SC,0,OUTPUT[d]); for(d=0;d<District;d++) lobj +=COST[d]*y[d][c]; Set the objective function CONSTRAINTS l1=0; l2=0;>= VOLUME[c]);  /* "Size": cover the required volume */
  p.newCtr("Min", l2 >= 2 ); 	/* "Min": at least 2 districts per contract */
 }
 
 for(d=0;d<District;d++)        /* Do not exceed max. output of any district */
 {
  l1=0;
  for(c=0;c<Contract;c++)
   l1 += y[d][c];
  p.newCtr("Output", l1 <= 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++)
   p.newCtr("XY", x[d][c] <= y[d][c]);

/****SOLVING + OUTPUT****/
 p.loadMat();                   /* Load the matrix explicitly */
 op = p.getXPRSprob();          /* Retrieve the Optimizer problem */
 XPRSchgobjsense(op, XPRS_OBJ_MINIMIZE);  /* Set sense to minimization */
 XPRSmipoptimize(op, "");       /* Solve the MIP problem */

 XPRSgetintattrib(op, XPRS_MIPSTATUS, &stat);
                                /* Get the global (MIP) status */
 if((stat==XPRS_MIP_SOLUTION) || (stat==XPRS_MIP_OPTIMAL))
 {                              /* Test whether an integer solution was found */
  XPRSgetdblattrib(op, XPRS_MIPOBJVAL, &val);   
  cout << "Objective: " << val << endl;
  XPRSgetintattrib(op, XPRS_ORIGINALCOLS, &ncol); 
  sol = new double[ncol];
  XPRSgetmipsol(op, sol, NULL); /* Get the primal solution values */
  XPRSgetnamelist(op, 2, NULL, 0, &len, 0, ncol-1);    
                        /* Get number of bytes required for retrieving names */
  names = new char[len];
  XPRSgetnamelist(op, 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)
    cout << names+offset << ": " << sol[i] << ", ";   
   offset += strlen(names+offset)+1;
  }     
  cout << endl;  
 }

 return 0;
}