    001package org.cpsolver.studentsct.heuristics.selection;
    002
    003import java.util.ArrayList;
    004import java.util.Collections;
    005import java.util.LinkedList;
    006import java.util.List;
    007
    008import org.cpsolver.ifs.solver.Solver;
    009import org.cpsolver.ifs.util.DataProperties;
    010import org.cpsolver.ifs.util.Progress;
    011import org.cpsolver.studentsct.heuristics.RandomizedBacktrackNeighbourSelection;
    012import org.cpsolver.studentsct.model.Enrollment;
    013import org.cpsolver.studentsct.model.Request;
    014import org.cpsolver.studentsct.model.Request.RequestPriority;
    015
    016/**
    017 * Use backtrack neighbour selection. For all unassigned variables (in a random
    018 * order) that are marked as critical, {@link RandomizedBacktrackNeighbourSelection} is being used.
    019 *
    020 * <br>
    021 * <br>
    022 *
    023 * @author  Tomáš Müller
    024 * @version StudentSct 1.3 (Student Sectioning)<br>
    025 *          Copyright (C) 2007 - 2014 Tomáš Müller<br>
    026 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    027 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    028 * <br>
    029 *          This library is free software; you can redistribute it and/or modify
    030 *          it under the terms of the GNU Lesser General Public License as
    031 *          published by the Free Software Foundation; either version 3 of the
    032 *          License, or (at your option) any later version. <br>
    033 * <br>
    034 *          This library is distributed in the hope that it will be useful, but
    035 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    036 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    037 *          Lesser General Public License for more details. <br>
    038 * <br>
    039 *          You should have received a copy of the GNU Lesser General Public
    040 *          License along with this library; if not see
    041 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    042 */
    043public class CriticalBacktrackSelection extends BacktrackSelection {
    044    private RequestPriority iPriority;
    045
    046    public CriticalBacktrackSelection(DataProperties properties, RequestPriority priority) {
    047        super(properties);
    048        iPriority = priority;
    049        iIncludeAssignedRequests = properties.getPropertyBoolean("Neighbour.IncludeCriticalAssignedRequests", iIncludeAssignedRequests);
    050    }
    051
    052    public CriticalBacktrackSelection(DataProperties properties) {
    053        this(properties, RequestPriority.Critical);
    054    }
    055
    056    @Override
    057    public void init(Solver<Request, Enrollment> solver, String name) {
    058        List<Request> variables = new ArrayList<Request>();
    059        for (Request r: (iIncludeAssignedRequests ? solver.currentSolution().getModel().variables() : solver.currentSolution().getModel().unassignedVariables(solver.currentSolution().getAssignment())))
    060            if (iPriority.isCritical(r)) variables.add(r);
    061        Collections.shuffle(variables);
    062        Collections.sort(variables, iRequestComparator);
    063        iRequests = new LinkedList<Request>(variables);
    064        if (iRBtNSel == null) {
    065            try {
    066                iRBtNSel = new RandomizedBacktrackNeighbourSelection(solver.getProperties());
    067                iRBtNSel.init(solver);
    068            } catch (Exception e) {
    069                throw new RuntimeException(e.getMessage(), e);
    070            }
    071        }
    072        Progress.getInstance(solver.currentSolution().getModel()).setPhase(iPriority.name() + " Backtracking" + (iFilter == null ? "" : " (" + iFilter.getName().toLowerCase() + " students)") + "...", variables.size());
    073    }
    074
    075}