001package org.cpsolver.coursett.neighbourhoods;
002
003import java.util.List;
004
005import org.cpsolver.coursett.model.Lecture;
006import org.cpsolver.coursett.model.Placement;
007import org.cpsolver.coursett.model.RoomLocation;
008import org.cpsolver.coursett.model.TimetableModel;
009import org.cpsolver.ifs.algorithms.neighbourhoods.RandomMove;
010import org.cpsolver.ifs.assignment.Assignment;
011import org.cpsolver.ifs.model.Neighbour;
012import org.cpsolver.ifs.model.SimpleNeighbour;
013import org.cpsolver.ifs.solution.Solution;
014import org.cpsolver.ifs.util.DataProperties;
015import org.cpsolver.ifs.util.ToolBox;
016
017
018/**
019 * Try to assign a class with a new room. A class is selected randomly, a
020 * different (available) room is randomly selected for the class -- the class is
021 * assigned into the new room if there is no conflict.
022 * <br>
023 * 
024 * @version IFS 1.3 (Iterative Forward Search)<br>
025 *          Copyright (C) 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 RoomChange extends RandomMove<Lecture, Placement> {
044
045    public RoomChange(DataProperties config) {
046        super(config);
047    }
048
049    @Override
050    public Neighbour<Lecture, Placement> selectNeighbour(Solution<Lecture, Placement> solution) {
051        TimetableModel model = (TimetableModel)solution.getModel();
052        Assignment<Lecture, Placement> assignment = solution.getAssignment();
053        int varIdx = ToolBox.random(model.variables().size());
054        for (int i = 0; i < model.variables().size(); i++) {
055            Lecture lecture = model.variables().get((i + varIdx) % model.variables().size());
056            Placement old = assignment.getValue(lecture);
057            if (old == null || old.getNrRooms() != 1) continue;
058
059            List<RoomLocation> values = lecture.roomLocations();
060            if (values.isEmpty()) continue;
061
062            int valIdx = ToolBox.random(values.size());
063            for (int j = 0; j < values.size(); j++) {
064                RoomLocation room = values.get((j + valIdx) % values.size());
065                if (room.getPreference() > 50) continue;
066                if (room.equals(old.getRoomLocation())) continue;
067                
068                Placement placement = new Placement(lecture, old.getTimeLocation(), room);
069                if (placement.isValid() && !model.inConflict(assignment, placement)) {
070                    SimpleNeighbour<Lecture, Placement> n = new SimpleNeighbour<Lecture, Placement>(lecture, placement);
071                    if (!iHC || n.value(assignment) <= 0) return n;
072                }
073            }
074        }
075        return null;
076    }
077}