    001package net.sf.cpsolver.coursett.neighbourhoods;
    002
    003import java.util.ArrayList;
    004import java.util.HashMap;
    005import java.util.List;
    006import java.util.Map;
    007import java.util.Set;
    008
    009import net.sf.cpsolver.coursett.model.Lecture;
    010import net.sf.cpsolver.coursett.model.Placement;
    011import net.sf.cpsolver.coursett.model.RoomLocation;
    012import net.sf.cpsolver.coursett.model.TimeLocation;
    013import net.sf.cpsolver.coursett.model.TimetableModel;
    014import net.sf.cpsolver.ifs.algorithms.neighbourhoods.RandomSwapMove;
    015import net.sf.cpsolver.ifs.model.Neighbour;
    016import net.sf.cpsolver.ifs.model.SimpleNeighbour;
    017import net.sf.cpsolver.ifs.solution.Solution;
    018import net.sf.cpsolver.ifs.solver.Solver;
    019import net.sf.cpsolver.ifs.util.DataProperties;
    020import net.sf.cpsolver.ifs.util.JProf;
    021import net.sf.cpsolver.ifs.util.ToolBox;
    022
    023/**
    024 * Try to assign a class with a new time. A class is selected randomly, a
    025 * different time is randomly selected for the class -- the class is
    026 * assigned into the new time. If the time is used or there is some other conflict,
    027 * it tries to resolve these conflicts by assigning conflicting classes to other
    028 * times as well.
    029 * <br>
    030 *
    031 * @version IFS 1.2 (Iterative Forward Search)<br>
    032 *          Copyright (C) 2014 Tomáš Müller<br>
    033 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    034 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    035 * <br>
    036 *          This library is free software; you can redistribute it and/or modify
    037 *          it under the terms of the GNU Lesser General Public License as
    038 *          published by the Free Software Foundation; either version 3 of the
    039 *          License, or (at your option) any later version. <br>
    040 * <br>
    041 *          This library is distributed in the hope that it will be useful, but
    042 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    043 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    044 *          Lesser General Public License for more details. <br>
    045 * <br>
    046 *          You should have received a copy of the GNU Lesser General Public
    047 *          License along with this library; if not see
    048 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    049 */
    050public class TimeSwap extends RandomSwapMove<Lecture, Placement> {
    051
    052    public TimeSwap(DataProperties config) {
    053        super(config);
    054    }
    055
    056    @Override
    057    public void init(Solver<Lecture, Placement> solver) {
    058    }
    059
    060    @Override
    061    public Neighbour<Lecture, Placement> selectNeighbour(Solution<Lecture, Placement> solution) {
    062        TimetableModel model = (TimetableModel)solution.getModel();
    063        double total = model.getTotalValue();
    064        int varIdx = ToolBox.random(model.variables().size());
    065        for (int i = 0; i < model.variables().size(); i++) {
    066            Lecture lecture = model.variables().get((i + varIdx) % model.variables().size());
    067            Placement old = lecture.getAssignment();
    068            if (old == null) continue;
    069
    070            List<TimeLocation> values = lecture.timeLocations();
    071            if (values.isEmpty()) continue;
    072
    073            int attempts = 0;
    074            long startTime = JProf.currentTimeMillis();
    075            int valIdx = ToolBox.random(values.size());
    076            for (int j = 0; j < values.size(); j++) {
    077                TimeLocation time = values.get((j + valIdx) % values.size());
    078                if (time.getPreference() > 50) continue;
    079                if (time.equals(old.getTimeLocation())) continue;
    080
    081                Placement placement = null;
    082                if (lecture.getNrRooms() == 0)
    083                    placement = new Placement(lecture, time, (RoomLocation) null);
    084                else if (lecture.getNrRooms() == 1)
    085                    placement = new Placement(lecture, time, old.getRoomLocation());
    086                else
    087                    placement = new Placement(lecture, time, old.getRoomLocations());
    088                if (!placement.isValid()) continue;
    089
    090                Set<Placement> conflicts = model.conflictValues(placement);
    091                if (conflicts.contains(placement)) continue;
    092                if (conflicts.isEmpty()) {
    093                    SimpleNeighbour<Lecture, Placement> n = new SimpleNeighbour<Lecture, Placement>(lecture, placement);
    094                    if (!iHC || n.value() <= 0) return n;
    095                    else continue;
    096                }
    097
    098                Map<Lecture, Placement> assignments = new HashMap<Lecture, Placement>();
    099                assignments.put(lecture, placement);
    100
    101                for (Placement conflict: conflicts)
    102                    conflict.variable().unassign(solution.getIteration());
    103                lecture.assign(solution.getIteration(), placement);
    104
    105                Double v = resolve(solution, total, startTime, assignments, new ArrayList<Placement>(conflicts), 0);
    106                if (!conflicts.isEmpty())
    107                    attempts ++;
    108
    109                lecture.unassign(solution.getIteration());
    110                for (Placement conflict: conflicts)
    111                    conflict.variable().assign(solution.getIteration(), conflict);
    112                lecture.assign(solution.getIteration(), old);
    113
    114                if (v != null)
    115                    return new SwapNeighbour(assignments.values(), v);
    116
    117                if (attempts >= iMaxAttempts) break;
    118            }
    119        }
    120        return null;
    121    }
    122
    123
    124    @Override
    125    public Double resolve(Solution<Lecture, Placement> solution, double total, long startTime, Map<Lecture, Placement> assignments, List<Placement> conflicts, int index) {
    126        if (index == conflicts.size()) return solution.getModel().getTotalValue() - total;
    127        Placement conflict = conflicts.get(index);
    128        Lecture variable = conflict.variable();
    129
    130        List<TimeLocation> values = variable.timeLocations();
    131        if (values.isEmpty()) return null;
    132
    133        int valIdx = ToolBox.random(values.size());
    134        int attempts = 0;
    135        for (int i = 0; i < values.size(); i++) {
    136            TimeLocation time = values.get((i + valIdx) % values.size());
    137            if (time.getPreference() > 50) continue;
    138            if (time.equals(conflict.getTimeLocation())) continue;
    139
    140            Placement value = null;
    141            if (variable.getNrRooms() == 0)
    142                value = new Placement(variable, time, (RoomLocation) null);
    143            else if (variable.getNrRooms() == 1)
    144                value = new Placement(variable, time, conflict.getRoomLocation());
    145            else
    146                value = new Placement(variable, time, conflict.getRoomLocations());
    147            if (!value.isValid() || solution.getModel().inConflict(value)) continue;
    148
    149            variable.assign(solution.getIteration(), value);
    150            Double v = resolve(solution, total, startTime, assignments, conflicts, 1 + index);
    151            variable.unassign(solution.getIteration());
    152            attempts ++;
    153
    154            if (v != null && (!iHC || v <= 0)) {
    155                assignments.put(variable, value);
    156                return v;
    157            }
    158            if (attempts >= iMaxAttempts || isTimeLimitReached(startTime)) break;
    159        }
    160
    161        return null;
    162    }
    163}