001package net.sf.cpsolver.coursett.neighbourhoods;
002
003import java.util.List;
004
005import net.sf.cpsolver.coursett.model.Lecture;
006import net.sf.cpsolver.coursett.model.Placement;
007import net.sf.cpsolver.coursett.model.RoomLocation;
008import net.sf.cpsolver.coursett.model.TimetableModel;
009import net.sf.cpsolver.ifs.algorithms.neighbourhoods.RandomMove;
010import net.sf.cpsolver.ifs.model.Neighbour;
011import net.sf.cpsolver.ifs.model.SimpleNeighbour;
012import net.sf.cpsolver.ifs.solution.Solution;
013import net.sf.cpsolver.ifs.util.DataProperties;
014import net.sf.cpsolver.ifs.util.ToolBox;
015
016/**
017 * Try to assign a class with a new room. A class is selected randomly, a
018 * different (available) room is randomly selected for the class -- the class is
019 * assigned into the new room if there is no conflict.
020 * <br>
021 * 
022 * @version IFS 1.2 (Iterative Forward Search)<br>
023 *          Copyright (C) 2014 Tomáš Müller<br>
024 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
025 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
026 * <br>
027 *          This library is free software; you can redistribute it and/or modify
028 *          it under the terms of the GNU Lesser General Public License as
029 *          published by the Free Software Foundation; either version 3 of the
030 *          License, or (at your option) any later version. <br>
031 * <br>
032 *          This library is distributed in the hope that it will be useful, but
033 *          WITHOUT ANY WARRANTY; without even the implied warranty of
034 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
035 *          Lesser General Public License for more details. <br>
036 * <br>
037 *          You should have received a copy of the GNU Lesser General Public
038 *          License along with this library; if not see
039 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
040 */
041public class RoomChange extends RandomMove<Lecture, Placement> {
042
043    public RoomChange(DataProperties config) {
044        super(config);
045    }
046
047    @Override
048    public Neighbour<Lecture, Placement> selectNeighbour(Solution<Lecture, Placement> solution) {
049        TimetableModel model = (TimetableModel)solution.getModel();
050        int varIdx = ToolBox.random(model.variables().size());
051        for (int i = 0; i < model.variables().size(); i++) {
052            Lecture lecture = model.variables().get((i + varIdx) % model.variables().size());
053            Placement old = lecture.getAssignment();
054            if (old == null || old.getNrRooms() != 1) continue;
055
056            List<RoomLocation> values = lecture.roomLocations();
057            if (values.isEmpty()) continue;
058
059            int valIdx = ToolBox.random(values.size());
060            for (int j = 0; j < values.size(); j++) {
061                RoomLocation room = values.get((j + valIdx) % values.size());
062                if (room.getPreference() > 50) continue;
063                if (room.equals(old.getRoomLocation())) continue;
064                
065                Placement placement = new Placement(lecture, old.getTimeLocation(), room);
066                if (placement.isValid() && !model.inConflict(placement)) {
067                    SimpleNeighbour<Lecture, Placement> n = new SimpleNeighbour<Lecture, Placement>(lecture, placement);
068                    if (!iHC || n.value() <= 0) return n;
069                }
070            }
071        }
072        return null;
073    }
074}