/******************************************************** Xpress-BCL C# Example Problems ============================== file xbexpl1i.cs ```````````````` BCL user guide example. Version using index sets. (c) 2008 Fair Isaac Corporation authors: S.Heipcke, D.Brett. ********************************************************/ using System; using System.Text; using System.IO; using BCL; namespace Examples { public class TestUGExpl1i { const int MAXNJ = 4; /* Max. number of jobs */ const int NT = 10; /* Time limit */ //Define XPRBDATAPATH to whatever folder you wish. const string XPRBDATAPATH = "../../data"; const string DATAFILE = XPRBDATAPATH + "/jobs/durations.dat"; /**** DATA ****/ int NJ = 0; /* Number of jobs read in */ double[] DUR = new double[MAXNJ]; /* Durations of jobs */ XPRBindexSet Jobs; /* Job names */ XPRBvar[] start; /* Start times of jobs */ XPRBvar[,] delta; /* Binaries for start times */ XPRBvar z; /* Maximum completion time (makespan) */ XPRBprob p = new XPRBprob("Jobs"); /* Initialize BCL and a new problem */ /*************************************************************************/ void readData() { string name; FileStream file; StreamReader fileStreamIn; /* Create a new index set */ Jobs = p.newIndexSet("jobs", MAXNJ); file = new FileStream(DATAFILE, FileMode.Open, FileAccess.Read); fileStreamIn = new StreamReader(file); object[] tempobj = new object[2]; while((NJ<MAXNJ) && (p.XPRBreadarrline(fileStreamIn, 99, "{t} , {g} ", out tempobj, 1) == 2))
            {
                int dummy;
                name = (string)tempobj[0];
                DUR[NJ] = (double)tempobj[1];
                dummy = Jobs + name;
                NJ++;
            }
    
            fileStreamIn.Close();
            file.Close();

            System.Console.WriteLine("Number of jobs read: " + Jobs.getSize());
        }

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

        void jobsModel()
        {
            XPRBexpr le;
            int j,t;

            /****VARIABLES****/
                /* Create start time variables (incl. bounds) */
            start = new XPRBvar[NJ];
            if(start==null) 
            { 
                System.Console.WriteLine("Not enough memory for 'start' variables.");
                return; 
            }
            for (j = 0; j < NJ; j++) start[j] = p.newVar("start", BCLconstant.XPRB_PL, 0, NT - DUR[j] + 1);
            z = p.newVar("z",BCLconstant.XPRB_PL,0,NT);  /* Declare the makespan variable */

            delta = new XPRBvar[NJ, NT];
            for(j=0;j<NJ;j++)              /* Declare binaries for each job  */
            {
                for(t=0;t<(NT-DUR[j]+1);t++)
                    delta[j,t] = p.newVar("delta" + Jobs.getIndexName(j) + "_" + (t+1), BCLconstant.XPRB_BV);
            }

            /****CONSTRAINTS****/
            for(j=0;j<NJ;j++)              /* Calculate maximal completion time */
                p.newCtr("Makespan", start[j]+DUR[j] <= z);

            p.newCtr("Prec", start[0]+DUR[0] <= start[2]);
                /* Precedence relation between jobs  */

            for(j=0;j<NJ;j++)              /* Linking start times and binaries  */ 
            { 
                le = new XPRBexpr(0);
                for(t=0;t<(NT-DUR[j]+1);t++)  le += (t+1)*delta[j,t]; 
                p.newCtr("Link_" + (j+1), le == start[j]);
            } 

            for(j=0;j<NJ;j++)              /* One unique start time for each job  */
            { 
                le = new XPRBexpr(0);
                for(t=0;t<(NT-DUR[j]+1);t++)  le += delta[j,t]; 
                p.newCtr("One_" + (j+1), le == 1);
            }      

            /****OBJECTIVE****/
            p.setObj(p.newCtr(z));                   /* Define and set objective function */ 

            jobsSolve();                   /* Solve the problem */

        } 

        /*************************************************************************/
        void jobsSolve()             
        { 
            int j,t,statmip; 

            for(j=0;j<NJ;j++)    
                for(t=0;t<NT-DUR[j]+1;t++)
                    delta[j,t].setDir(BCLconstant.XPRB_PR,10*(t+1)); 
                    /* Give highest priority to variables for earlier start times */

            p.setSense(BCLconstant.XPRB_MINIM);
            p.mipOptimize();                   /* Solve the problem as MIP */
            statmip = p.getMIPStat();       /* Get the MIP problem status */    

            if((statmip == BCLconstant.XPRB_MIP_SOLUTION) || (statmip == BCLconstant.XPRB_MIP_OPTIMAL))
                 /* An integer solution has been found */
            {  
                System.Console.WriteLine("Objective: " + p.getObjVal()); 
                for(j=0;j<NJ;j++) 
                {                              /* Print the solution for all start times */
                    System.Console.WriteLine(start[j].getName() + ": " + start[j].getSol()); 
                    for(t=0;t<NT-DUR[j]+1;t++) 
                        System.Console.Write(delta[j,t].getName() + ": " + delta[j,t].getSol() + " ");
                    System.Console.WriteLine();;
                }
            } 
        }

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

        public static void Main() 
        {
           XPRB.init();
           TestUGExpl1i TestInstance = new TestUGExpl1i();

            TestInstance.readData();                     /* Read in the data */
            TestInstance.jobsModel();                    /* Define and solve the problem */
            
            return;     
        }

    }

}