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