[Cbc] please help me

[刘峰]

Dear Sir:
         My name is LiuFeng, I am a student of Computer Science In Ji Lin
University of China. I am learning to use CBC Library to solve some MIP
problems. I met a problem,but I don't know how to solve it.
         The problem is as follows.
          It is an Integer Programming problem.
          The target function is Min z=x1 + x2 + x3 + x4
          The Constraints are
                                             4*x1 + 3*x2  +
2*x3             =2
                                                            x2 +  2*x3 +
5*x4 = 2
                                             xi >= 0 (i=1,2,3,4) all of
them have the constraint of integer.

          The CBC Codes is as follows:
int _tmain(int argc, _TCHAR* argv[])
{
     OsiClpSolverInterface solver1;
     const int numcols = 4;
     const int numrows = 2;
     int nnz = 6;
    CoinBigIndex *start = new int[numcols+1];
    int* index = new int[nnz];
    double* value = new double[nnz];
    double *collb = new double[numcols];
    double *colub = new double[numcols];
    double *obj = new double[numcols];
    double *rowlb = new double[numrows];
    double *rowub = new double[numrows];
 //object
 obj[0] = -1.0; obj[1] = -1.0; obj[2]=-1.0; obj[3]=-1.0;
  // column bounds
    collb[0] = 0;  colub[0] = solver1.getInfinity();
    collb[1] = 0;  colub[1] = solver1.getInfinity();
    collb[2] = 0;  colub[2] = solver1.getInfinity();
    collb[3] = 0;  colub[3] = solver1.getInfinity();
 // matrix
 start[0]=0; index[0] = 0; value[0] = 4.0;
 start[1]=1; index[1] = 0; value[4] = 3.0;
    index[2] = 1; value[5] = 1.0;
 start[2]=3; index[3] = 0; value[6] = 2.0;
    index[4] = 1; value[7] = 2.0;
 start[3]=5; index[5] = 1; value[8] = 5.0;
 start[4]=6;
 // row bounds
 rowlb[0] = 2.; rowub[0] = 2.;
    rowlb[1] = 2.; rowub[1] = 2.;
 solver1.loadProblem(numcols, numrows, start, index, value, collb, colub,
obj, rowlb, rowub);
 solver1.setInteger(0); // Sets x0 to integer
 solver1.setInteger(1); // Sets x1 to integer
 solver1.setInteger(2); // Sets x2 to integer
 solver1.setInteger(3); // Sets x3 to integer
 solver1.setObjSense(-1000.0); // Maximise
 CbcModel solver(solver1);
 solver.branchAndBound();
 bool optimal = solver.isProvenOptimal();
 const double *val = solver.getColSolution();
 printf("Solution %g %g %g %g\n", val[0], val[1], val[2], val[3]);
 return 0;
}

       I can't get the result. Would you please tell me how to solve
them?Thank you very much!
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