/**
* Initialization. Enforce arc-consistency over the current (initial) solution. AC3 algorithm is
* used.
*/
@Override
public boolean init(Solver<V, T> solver) {
boolean isOk = true;
iProgress = Progress.getInstance(getModel());
iProgress.save();
iProgress.setPhase("Initializing propagation:", getModel().variables().size());
for (Iterator<V> i = getModel().variables().iterator(); i.hasNext(); ) {
V aVariable = i.next();
supportValues(aVariable).clear();
goodValues(aVariable).clear();
}
List<T> queue = new ArrayList<T>();
for (Iterator<V> i = getModel().variables().iterator(); i.hasNext(); ) {
V aVariable = i.next();
for (Iterator<T> j = aVariable.values().iterator(); j.hasNext(); ) {
T aValue = j.next();
initNoGood(aValue, null);
goodValues(aVariable).add(aValue);
if (revise(aValue)) {
queue.add(aValue);
} else if (aVariable.getAssignment() != null && !aValue.equals(aVariable.getAssignment())) {
Set<T> noGood = new HashSet<T>();
noGood.add(aVariable.getAssignment());
setNoGood(aValue, noGood);
queue.add(aValue);
}
}
iProgress.incProgress();
}
propagate(queue);
iProgress.restore();
return isOk;
}
/**
* With the given probabilty, a problematic student is randomly selected to be unassigned. Null is
* returned otherwise.
*/
@Override
public Neighbour<Request, Enrollment> selectNeighbour(Solution<Request, Enrollment> solution) {
if (!iProblemStudents.isEmpty() && Math.random() < iRandom) {
Student student = ToolBox.random(iProblemStudents);
iProblemStudents.remove(student);
return new UnassignStudentNeighbour(student);
}
Progress.getInstance(solution.getModel()).incProgress();
return null;
}
/** Initialization -- {@link ProblemStudentsProvider#getProblemStudents()} is called */
@Override
public void init(Solver<Request, Enrollment> solver) {
iProblemStudents = iProblemStudentsProvider.getProblemStudents();
Progress.getInstance(solver.currentSolution().getModel())
.setPhase("Random unassignment of problematic students...", 1);
}