public void computeCourses() throws GRBException {
env = new GRBEnv();
env.set(GRB.IntParam.LogToConsole, 0);
model = new GRBModel(env);
y_ijk = new GRBVar[studentList.size()][classList.size()][semesterList.size()];
for (int a = 0; a < studentList.size(); a++) {
for (int b = 0; b < classList.size(); b++) {
for (int c = 0; c < semesterList.size(); c++) {
y_ijk[a][b][c] = model.addVar(0, 1, 0, GRB.BINARY, "Demand_" + a + b + c);
}
}
}
x = model.addVar(0, GRB.INFINITY, 0, GRB.INTEGER, null);
obj = new GRBLinExpr();
obj.addTerm(1, x);
model.set(GRB.IntAttr.ModelSense, 1);
model.update();
for (int a = 0; a < studentList.size(); a++) {
for (int b = 0; b < classList.size(); b++) {
GRBLinExpr studentClassListCon = new GRBLinExpr();
for (int c = 0; c < semesterList.size(); c++) {
studentClassListCon.addTerm(1, y_ijk[a][b][c]);
}
model.addConstr(studentClassListCon, GRB.EQUAL, A_s[a][b], "Student Schedule" + a + b);
}
}
// Set maximum seat capacity aka X
for (int c = 0; c < semesterList.size(); c++) {
for (int b = 0; b < classList.size(); b++) {
GRBLinExpr maxClassCapCon = new GRBLinExpr();
for (int a = 0; a < studentList.size(); a++) {
maxClassCapCon.addTerm(1, y_ijk[a][b][c]);
}
model.addConstr(maxClassCapCon, GRB.LESS_EQUAL, x, "X");
}
}
for (int a = 0; a < studentList.size(); a++) {
for (int c = 0; c < semesterList.size(); c++) {
GRBLinExpr maxClassCon = new GRBLinExpr();
for (int b = 0; b < classList.size(); b++) {
maxClassCon.addTerm(1, y_ijk[a][b][c]);
}
model.addConstr(maxClassCon, GRB.LESS_EQUAL, 2, "ClassLimit");
}
}
// Available Constriant
for (int a = 0; a < studentList.size(); a++) {
for (int b = 0; b < classList.size(); b++) {
GRBLinExpr classAvalCon = new GRBLinExpr();
for (int c = 0; c < semesterList.size(); c++) {
if (courseAvalMatrix[b][c] == 0) {
classAvalCon.addTerm(1, y_ijk[a][b][c]);
// System.out.printf("Course %d during Semester %d\n", (b + 1), (c + 1));
}
}
model.addConstr(classAvalCon, GRB.EQUAL, 0, "NotAval");
}
}
// Can't take first semester
for (int a = 0; a < studentList.size(); a++) {
GRBLinExpr firstSemesterCon = new GRBLinExpr();
for (int b = 0; b < classList.size(); b++) {
if (classList.get(b).preqCourseId != 0) {
firstSemesterCon.addTerm(1, y_ijk[a][b][0]);
}
}
model.addConstr(firstSemesterCon, GRB.EQUAL, 0, "firstSemester");
}
// Prereq Constraint
GRBLinExpr preReqConLeft = new GRBLinExpr();
GRBLinExpr preReqConRight = new GRBLinExpr();
for (int a = 0; a < studentList.size(); a++) {
for (int c = 0; c < (semesterList.size() - 1); c++) {
preReqConLeft.addTerm(1, y_ijk[a][15][c + 1]);
preReqConRight.addTerm(1, y_ijk[a][3][c]);
preReqConLeft.addTerm(1, y_ijk[a][0][c + 1]);
preReqConRight.addTerm(1, y_ijk[a][11][c]);
preReqConLeft.addTerm(1, y_ijk[a][12][c + 1]);
preReqConRight.addTerm(1, y_ijk[a][8][c]);
preReqConLeft.addTerm(1, y_ijk[a][6][c + 1]);
preReqConRight.addTerm(1, y_ijk[a][2][c]);
}
model.addConstr((preReqConRight), GRB.GREATER_EQUAL, preReqConLeft, "PrereqClass");
}
for (int b = 0; b < classList.size(); b++) {
for (int a = 0; a < studentList.size(); a++) {
GRBLinExpr mustTakeReq = new GRBLinExpr();
for (int c = 0; c < semesterList.size(); c++) {
for (int d = 0; d < studentList.get(a).demands.size(); d++) {
// System.out.print(studentList.get(a).demands.get(d).courseId);
if (preReqMatrix[(studentList.get(a).demands.get(d).courseId) - 1][b] == 1) {
mustTakeReq.addTerm(1, y_ijk[a][b][c]);
// System.out.printf("Student %d must takes Course %d \n", (a + 1), (b + 1));
}
}
}
// model.addConstr(mustTakeReq,GRB.EQUAL, 1, "Must Take");
}
}
model.setObjective(obj);
model.optimize();
int status = model.get(GRB.IntAttr.Status);
System.out.println("X = " + model.get(GRB.DoubleAttr.ObjVal));
}
/**
* Constructor
*
* @param ind
* @param N
* @param Us
* @param Ds
* @param ds
* @param OP
* @param SP
* @param bestLB
* @param fixTo1
* @param fixTo0
* @param varToFix
* @param valueToFix
* @throws GRBException
*/
public BBNode(
int ind,
int N,
Matrix Us,
Matrix Ds,
Matrix ds,
GRBModel OP,
GRBModel SP,
double bestLB,
List<GRBVar> fixTo1,
List<GRBVar> fixTo0,
GRBVar varToFix,
boolean valueToFix)
throws GRBException {
this.ind = ind;
this.Us = Us;
this.nodesBestUs = Us;
this.bestLB = bestLB;
this.varsFixedTo0.addAll(fixTo0);
this.varsFixedTo1.addAll(fixTo1);
if (valueToFix) this.varsFixedTo1.add(varToFix);
else this.varsFixedTo0.add(varToFix);
LR_Main.fixVar(varsFixedTo0, false, SP);
LR_Main.fixVar(varsFixedTo1, true, SP);
double miu;
int cntr = 0;
int k = 0;
SP.optimize();
if (SP.get(GRB.IntAttr.Status) != 3) { // Model feasibility check
UB = SP.get(GRB.DoubleAttr.ObjVal);
// System.out.println("miu: " + miu + " - Itr" + k + ": LB = " + lb.value + " - UB = " +
// UB);
while (
/*this.gap > optGap &&*/ k < 5) {
cntr = LR_Main.dissectEpsilon(cntr, 3);
// miu = LR_Main.updateMiu(miu, k, N);
miu = LR_Main.updateMiuC(Ds, ds);
this.Us = LR_Main.updateU(SP, miu, this.Us, ds, Ds); // Update Lagrangian multipliers
LR_Main.updateObjCoeffs(SP, this.Us, ds, Ds); // Update obj fun coefficients
SP.optimize();
UB = SP.get(GRB.DoubleAttr.ObjVal);
if (UB < this.bestUB) {
this.bestUB = UB;
cntr = 0;
} else {
cntr++;
}
this.selectedLocations = new ArrayList<String>();
for (int i = 1; i <= N; i++) {
GRBVar var = SP.getVar(SP.get(GRB.IntAttr.NumVars) - i);
if (var.get(GRB.DoubleAttr.X) > 0)
this.selectedLocations.add(var.get(GRB.StringAttr.VarName));
}
lb = LR_Main.obtainLB(OP, SP);
LR_Main.updateLB(lb.value);
k++; // Counter update
updateGap();
updateBestResult(this.lb, this.UB, this.Us, this.selectedLocations);
System.out.println(
"miu: "
+ miu
+ " - Itr"
+ k
+ ": LB="
+ lb.value
+ " - UB= "
+ UB
+ " - gap= "
+ this.gap
+ " - eps= "
+ LR_Main.epsilon);
}
updateNode(nodeBestUB, nodesBestLB, nodesBestUs, nodesBestSelectedLocations);
} else {
this.fathom = true;
}
// System.out.println("# of constraints: " + SP.get(GRB.IntAttr.NumConstrs));
noOfFixedVars = this.varsFixedTo0.size() + this.varsFixedTo1.size();
}