/******************************************************** Xpress-BCL C# Example Problems ============================== file xbcontr2.cs ```````````````` Contract allocation example. Combining BCL problem input with problem solving and callbacks in Xpress-Optimizer. --- MIP Single-threaded --- (c) 2008 Fair Isaac Corporation authors: S.Heipcke, D.Brett. ********************************************************/ using System; using System.Text; using System.IO; using Optimizer; using BCL; namespace Examples { public class TestUGContr2s { const int District = 6; /* Number of districts */ const int 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 */ /*********************************************************************/ public void printsolution(XPRSprob xprsp, object vp) { int num, d, c; XPRBprob bprob; XPRBvar y; bprob = (XPRBprob)vp; bprob.beginCB(xprsp); num = xprsp.MIPSols; bprob.sync(BCLconstant.XPRB_XPRS_SOL); /* Update BCL solution values */ System.Console.WriteLine("Solution " + num + ": Objective value: " + bprob.getObjVal()); for(d=0;d<District;d++) for(c=0;c<Contract;c++) y=bprob.getVarByName("q_d" +="c">-1) && (y.getSol() != 0))
                        System.Console.WriteLine(y.getName() + ": " + y.getSol()); 
                }
            bprob.endCB();

            return;
        }

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

        public static void Main()
        {
           XPRB.init();
           int d,c;
            XPRBexpr l1,l2,lobj;
            XPRBvar[,] x = new XPRBvar[District,Contract];  /* Variables indicating whether a project 
            is chosen */
            XPRBvar[,] y = new XPRBvar[District,Contract];  /* Quantities allocated to contractors */
            XPRBprob p = new XPRBprob("Contr2");           /* Initialize a new problem in BCL */
            TestUGContr2s TestInstance = new TestUGContr2s();
            IntsolCallback del = new IntsolCallback(TestInstance.printsolution);
            XPRSprob xprsp;

            /**** VARIABLES ****/
            for(d=0;d<District;d++) for(c=0;c<Contract;c++) c]=p.newVar("x_d" +="c" lobj=new for(d=0;d<District;d++) Set the objective function CONSTRAINTS l1=new l2=new>= TestInstance.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= new XPRBexpr(0);
                for(c=0;c<Contract;c++)
                    l1 += y[d,c];
                p.newCtr("Output", l1 <= TestInstance.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****/
            xprsp = p.getXPRSprob();
            /* Desactivate parallel MIP (for synchronization of BCL and Optimizer) */
            xprsp.MIPThreads = 1;
            xprsp.AddIntsolCallback(del, (object)p);
            /* Define an integer solution callback */

            p.setSense(BCLconstant.XPRB_MINIM);
            p.mipOptimize();

            return;
        } 

    }

}