/******************************************************** Xpress-BCL C# Example Problems ============================== file xbcontr1.cs ```````````````` Contract allocation example. Combining BCL problem input with problem solving in Xpress-Optimizer. (c) 2008-2023 Fair Isaac Corporation authors: S.Heipcke, D.Brett. ********************************************************/ using System; using System.Text; using System.IO; using Optimizer; using BCL; namespace Examples { public class TestUGContr1 { 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 static void Main() { XPRB.init(); int d,c; XPRBexpr l1,l2,lobj; /* Variables indicating whether a project is chosen */ XPRBvar[,] x = new XPRBvar[District,Contract]; /* Quantities allocated to contractors */ XPRBvar[,] y = new XPRBvar[District,Contract]; int i, ncol, len, stat; double[] sol; double val; /* Initialize a new problem in BCL */ XPRBprob p = new XPRBprob("Contr1"); XPRSprob xprsp; TestUGContr1 TestInstance = new TestUGContr1(); /**** VARIABLES ****/ for(d=0;d<District;d++) for(c=0;c<Contract;c++) x[d,c]=p.newVar("x_d" +="c" y[d,c]=p.newVar("q_d" lobj=new for(d=0;d<District;d++) Set the objective function CONSTRAINTS l1=new l2=new /*="Size" : cover required volume>= TestInstance.VOLUME[c]);

                /* "Min": at least 2 districts per contract */
                p.newCtr("Min", l2 >= 2 );
            }

	    /* Do not exceed max. output of any district */
            for(d=0;d<District;d++)
            {
                l1 = new XPRBexpr();
                for(c=0;c<Contract;c++)
                l1 += y[d,c];
                p.newCtr("Output", l1 <= TestInstance.OUTPUT[d]);
            }

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

            /****SOLVING + OUTPUT****/
            p.loadMat();                   /* Load the matrix explicitly */
            xprsp = p.getXPRSprob();
            xprsp.ChgObjSense(ObjSense.Minimize);
            xprsp.MipOptimize();              /* Solve the MIP problem */

            stat = (int)xprsp.MIPStatus;
            /* Get the global (MIP) status */

	    /* Test whether an integer solution was found */
            if (((int)MIPStatus.Solution==stat) ||
            	((int)MIPStatus.Optimal==stat))
            {
                val = xprsp.MIPObjVal;
                System.Console.WriteLine("Objective: " + val);

                ncol = xprsp.Cols;
                sol = new double[ncol];

                xprsp.GetMipSol(sol);
                /* Get the primal solution values */
                len = xprsp.NameLength;
                /* Get the maximum name length */


                string[] names = xprsp.GetNames(2, 0, ncol - 1);
                // Get the variable names
                for (i = 0; i < ncol; i++)         // Print out the solution
                    if (sol[i] != 0)
                    {
                        System.Console.Write(names[i] + ": " + sol[i] + ", ");
                    }
                System.Console.WriteLine();

            }

            return;
        }

    }

}