    001package org.cpsolver.coursett.neighbourhoods;
    002
    003import java.util.ArrayList;
    004import java.util.HashMap;
    005import java.util.List;
    006import java.util.Map;
    007import java.util.Set;
    008import java.util.concurrent.locks.Lock;
    009
    010import org.cpsolver.coursett.model.Lecture;
    011import org.cpsolver.coursett.model.Placement;
    012import org.cpsolver.coursett.model.RoomLocation;
    013import org.cpsolver.coursett.model.TimeLocation;
    014import org.cpsolver.coursett.model.TimetableModel;
    015import org.cpsolver.ifs.algorithms.neighbourhoods.RandomSwapMove;
    016import org.cpsolver.ifs.assignment.Assignment;
    017import org.cpsolver.ifs.model.Neighbour;
    018import org.cpsolver.ifs.model.SimpleNeighbour;
    019import org.cpsolver.ifs.solution.Solution;
    020import org.cpsolver.ifs.solver.Solver;
    021import org.cpsolver.ifs.util.DataProperties;
    022import org.cpsolver.ifs.util.JProf;
    023import org.cpsolver.ifs.util.ToolBox;
    024
    025
    026/**
    027 * Try to assign a class with a new time. A class is selected randomly, a
    028 * different time is randomly selected for the class -- the class is
    029 * assigned into the new time. If the time is used or there is some other conflict,
    030 * it tries to resolve these conflicts by assigning conflicting classes to other
    031 * times as well.
    032 * <br>
    033 *
    034 * @author  Tomáš Müller
    035 * @version IFS 1.3 (Iterative Forward Search)<br>
    036 *          Copyright (C) 2014 Tomáš Müller<br>
    037 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    038 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    039 * <br>
    040 *          This library is free software; you can redistribute it and/or modify
    041 *          it under the terms of the GNU Lesser General Public License as
    042 *          published by the Free Software Foundation; either version 3 of the
    043 *          License, or (at your option) any later version. <br>
    044 * <br>
    045 *          This library is distributed in the hope that it will be useful, but
    046 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    047 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    048 *          Lesser General Public License for more details. <br>
    049 * <br>
    050 *          You should have received a copy of the GNU Lesser General Public
    051 *          License along with this library; if not see
    052 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    053 */
    054public class TimeSwap extends RandomSwapMove<Lecture, Placement> {
    055
    056    public TimeSwap(DataProperties config) {
    057        super(config);
    058    }
    059
    060    @Override
    061    public void init(Solver<Lecture, Placement> solver) {
    062    }
    063
    064    @Override
    065    public Neighbour<Lecture, Placement> selectNeighbour(Solution<Lecture, Placement> solution) {
    066        TimetableModel model = (TimetableModel)solution.getModel();
    067        Assignment<Lecture, Placement> assignment = solution.getAssignment();
    068        double total = model.getTotalValue(assignment);
    069        int varIdx = ToolBox.random(model.variables().size());
    070        for (int i = 0; i < model.variables().size(); i++) {
    071            Lecture lecture = model.variables().get((i + varIdx) % model.variables().size());
    072            Placement old = lecture.getAssignment(assignment);
    073            if (old == null) continue;
    074
    075            List<TimeLocation> values = lecture.timeLocations();
    076            if (values.isEmpty()) continue;
    077
    078            Lock lock = solution.getLock().writeLock();
    079            lock.lock();
    080            try {
    081                int attempts = 0;
    082                long startTime = JProf.currentTimeMillis();
    083                int valIdx = ToolBox.random(values.size());
    084                for (int j = 0; j < values.size(); j++) {
    085                    TimeLocation time = values.get((j + valIdx) % values.size());
    086                    if (time.getPreference() > 50) continue;
    087                    if (time.equals(old.getTimeLocation())) continue;
    088
    089                    Placement placement = null;
    090                    if (lecture.getNrRooms() == 0)
    091                        placement = new Placement(lecture, time, (RoomLocation) null);
    092                    else if (lecture.getNrRooms() == 1)
    093                        placement = new Placement(lecture, time, old.getRoomLocation());
    094                    else
    095                        placement = new Placement(lecture, time, old.getRoomLocations());
    096                    if (!placement.isValid()) continue;
    097
    098                    Set<Placement> conflicts = model.conflictValues(assignment, placement);
    099                    if (conflicts.contains(placement)) continue;
    100                    if (conflicts.isEmpty()) {
    101                        SimpleNeighbour<Lecture, Placement> n = new SimpleNeighbour<Lecture, Placement>(lecture, placement);
    102                        if (!iHC || n.value(assignment) <= 0) return n;
    103                        else continue;
    104                    }
    105
    106                    Map<Lecture, Placement> assignments = new HashMap<Lecture, Placement>();
    107                    assignments.put(lecture, placement);
    108
    109                    for (Placement conflict: conflicts)
    110                        assignment.unassign(solution.getIteration(), conflict.variable());
    111                    assignment.assign(solution.getIteration(), placement);
    112
    113                    Double v = resolve(solution, total, startTime, assignments, new ArrayList<Placement>(conflicts), 0);
    114                    if (!conflicts.isEmpty())
    115                        attempts ++;
    116
    117                    assignment.unassign(solution.getIteration(), lecture);
    118                    for (Placement conflict: conflicts)
    119                        assignment.assign(solution.getIteration(), conflict);
    120                    assignment.assign(solution.getIteration(), old);
    121
    122                    if (v != null)
    123                        return new SwapNeighbour(assignments.values(), v);
    124
    125                    if (attempts >= iMaxAttempts) break;
    126                }
    127            } finally {
    128                lock.unlock();
    129            }
    130        }
    131        return null;
    132    }
    133
    134
    135    @Override
    136    public Double resolve(Solution<Lecture, Placement> solution, double total, long startTime, Map<Lecture, Placement> assignments, List<Placement> conflicts, int index) {
    137        Assignment<Lecture, Placement> assignment = solution.getAssignment();
    138
    139        if (index == conflicts.size()) return solution.getModel().getTotalValue(assignment) - total;
    140        Placement conflict = conflicts.get(index);
    141        Lecture variable = conflict.variable();
    142
    143        List<TimeLocation> values = variable.timeLocations();
    144        if (values.isEmpty()) return null;
    145
    146        int valIdx = ToolBox.random(values.size());
    147        int attempts = 0;
    148        for (int i = 0; i < values.size(); i++) {
    149            TimeLocation time = values.get((i + valIdx) % values.size());
    150            if (time.getPreference() > 50) continue;
    151            if (time.equals(conflict.getTimeLocation())) continue;
    152
    153            Placement value = null;
    154            if (variable.getNrRooms() == 0)
    155                value = new Placement(variable, time, (RoomLocation) null);
    156            else if (variable.getNrRooms() == 1)
    157                value = new Placement(variable, time, conflict.getRoomLocation());
    158            else
    159                value = new Placement(variable, time, conflict.getRoomLocations());
    160            if (!value.isValid() || solution.getModel().inConflict(assignment, value)) continue;
    161
    162            assignment.assign(solution.getIteration(), value);
    163            Double v = resolve(solution, total, startTime, assignments, conflicts, 1 + index);
    164            assignment.unassign(solution.getIteration(), variable);
    165            attempts ++;
    166
    167            if (v != null && (!iHC || v <= 0)) {
    168                assignments.put(variable, value);
    169                return v;
    170            }
    171            if (attempts >= iMaxAttempts || isTimeLimitReached(startTime)) break;
    172        }
    173
    174        return null;
    175    }
    176}