001package net.sf.cpsolver.exam.neighbours;
002
003import java.text.DecimalFormat;
004import java.util.ArrayList;
005import java.util.HashSet;
006import java.util.Iterator;
007import java.util.List;
008import java.util.Set;
009
010import net.sf.cpsolver.exam.model.Exam;
011import net.sf.cpsolver.exam.model.ExamModel;
012import net.sf.cpsolver.exam.model.ExamPlacement;
013import net.sf.cpsolver.exam.model.ExamRoomPlacement;
014import net.sf.cpsolver.exam.model.ExamRoomSharing;
015import net.sf.cpsolver.ifs.model.Neighbour;
016
017/**
018 * Swap a room between two assigned exams. <br>
019 * <br>
020 * 
021 * @version ExamTT 1.2 (Examination Timetabling)<br>
022 *          Copyright (C) 2008 - 2010 Tomáš Müller<br>
023 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
024 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
025 * <br>
026 *          This library is free software; you can redistribute it and/or modify
027 *          it under the terms of the GNU Lesser General Public License as
028 *          published by the Free Software Foundation; either version 3 of the
029 *          License, or (at your option) any later version. <br>
030 * <br>
031 *          This library is distributed in the hope that it will be useful, but
032 *          WITHOUT ANY WARRANTY; without even the implied warranty of
033 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
034 *          Lesser General Public License for more details. <br>
035 * <br>
036 *          You should have received a copy of the GNU Lesser General Public
037 *          License along with this library; if not see
038 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
039 */
040public class ExamRoomSwapNeighbour extends Neighbour<Exam, ExamPlacement> {
041    private double iValue = 0;
042    private ExamPlacement iX1, iX2 = null;
043    private ExamRoomPlacement iR1, iR2 = null;
044
045    public ExamRoomSwapNeighbour(ExamPlacement placement, ExamRoomPlacement current, ExamRoomPlacement swap) {
046        if (placement.getRoomPlacements().contains(swap))
047            return; // not an actual swap
048        Exam exam = placement.variable();
049        if (!swap.isAvailable(placement.getPeriod()))
050            return; // room not available
051        if (!exam.checkDistributionConstraints(swap))
052            return; // a distribution constraint is violated
053        int size = 0;
054        for (ExamRoomPlacement r : placement.getRoomPlacements())
055            size += r.getSize(exam.hasAltSeating());
056        size -= current.getSize(exam.hasAltSeating());
057        size += swap.getSize(exam.hasAltSeating());
058        if (size < exam.getSize())
059            return; // new room is too small
060        ExamPlacement conflict = null;
061        ExamRoomSharing rs = ((ExamModel)exam.getModel()).getRoomSharing();
062        if (rs != null && placement.getRoomPlacements().size() == 1) {
063            Set<ExamPlacement> x = new HashSet<ExamPlacement>();
064            rs.computeConflicts(exam, swap.getRoom().getPlacements(placement.getPeriod()), swap.getRoom(), x);
065            if (x.size() > 1) return;
066            else if (x.size() == 1) conflict = x.iterator().next();
067        } else {
068            List<ExamPlacement> conf = swap.getRoom().getPlacements(placement.getPeriod());
069            if (conf.size() > 1) return;
070            else if (conf.size() == 1) conflict = conf.get(0);
071        }
072        if (conflict == null) {
073            Set<ExamRoomPlacement> newRooms = new HashSet<ExamRoomPlacement>(placement.getRoomPlacements());
074            newRooms.remove(current);
075            newRooms.add(swap);
076            for (Iterator<ExamRoomPlacement> i = newRooms.iterator(); i.hasNext();) {
077                ExamRoomPlacement r = i.next();
078                if (r.equals(swap))
079                    continue;
080                if (size - r.getSize(exam.hasAltSeating()) >= exam.getSize()) {
081                    i.remove();
082                    size -= r.getSize(exam.hasAltSeating());
083                }
084            }
085            iX1 = new ExamPlacement(exam, placement.getPeriodPlacement(), newRooms);
086            iValue = iX1.toDouble() - (exam.getAssignment() == null ? 0.0 : exam.getAssignment().toDouble());
087        } else {
088            Exam x = conflict.variable();
089            ExamRoomPlacement xNew = x.getRoomPlacement(current.getRoom());
090            if (xNew == null)
091                return; // conflicting exam cannot be assigned in the current
092                        // room
093            if (!x.checkDistributionConstraints(xNew))
094                return; // conflicting exam has a distribution constraint
095                        // violated
096            int xSize = 0;
097            for (ExamRoomPlacement r : conflict.getRoomPlacements()) {
098                xSize += r.getSize(x.hasAltSeating());
099            }
100            xSize -= swap.getSize(x.hasAltSeating());
101            xSize += current.getSize(x.hasAltSeating());
102            if (xSize < x.getSize())
103                return; // current room is too small for the conflicting exam
104            if (rs != null) {
105                List<ExamPlacement> other = new ArrayList<ExamPlacement>(current.getRoom().getPlacements(conflict.getPeriod()));
106                other.remove(placement);
107                if (!other.isEmpty() && conflict.getRoomPlacements().size() > 1) return;
108                if (rs.inConflict(x, other, current.getRoom())) return;
109            }
110            Set<ExamRoomPlacement> newRooms = new HashSet<ExamRoomPlacement>(placement.getRoomPlacements());
111            newRooms.remove(current);
112            newRooms.add(swap);
113            for (Iterator<ExamRoomPlacement> i = newRooms.iterator(); i.hasNext();) {
114                ExamRoomPlacement r = i.next();
115                if (r.equals(swap))
116                    continue;
117                if (size - r.getSize(exam.hasAltSeating()) >= exam.getSize()) {
118                    i.remove();
119                    size -= r.getSize(exam.hasAltSeating());
120                }
121            }
122            iX1 = new ExamPlacement(exam, placement.getPeriodPlacement(), newRooms);
123            Set<ExamRoomPlacement> xRooms = new HashSet<ExamRoomPlacement>(conflict.getRoomPlacements());
124            xRooms.remove(x.getRoomPlacement(swap.getRoom()));
125            xRooms.add(xNew);
126            for (Iterator<ExamRoomPlacement> i = xRooms.iterator(); i.hasNext();) {
127                ExamRoomPlacement r = i.next();
128                if (r.equals(swap))
129                    continue;
130                if (xSize - r.getSize(x.hasAltSeating()) >= x.getSize()) {
131                    i.remove();
132                    xSize -= r.getSize(x.hasAltSeating());
133                }
134            }
135            iX2 = new ExamPlacement(x, conflict.getPeriodPlacement(), xRooms);
136            iValue = iX1.toDouble() - (exam.getAssignment() == null ? 0.0 : exam.getAssignment().toDouble())
137                    + iX2.toDouble() - conflict.toDouble();
138        }
139        iR1 = current;
140        iR2 = swap;
141    }
142
143    public boolean canDo() {
144        return iX1 != null;
145    }
146
147    @Override
148    public void assign(long iteration) {
149        if (iX2 == null) {
150            iX1.variable().assign(iteration, iX1);
151        } else {
152            if (iX1.variable().getAssignment() != null)
153                iX1.variable().unassign(iteration);
154            iX2.variable().unassign(iteration);
155            iX1.variable().assign(iteration, iX1);
156            iX2.variable().assign(iteration, iX2);
157        }
158    }
159
160    @Override
161    public String toString() {
162        if (iX2 == null) {
163            return iX1.variable().getAssignment() + " -> " + iX1.toString() + " / " + " (value:" + value() + ")";
164        } else {
165            return iX1.variable().getName() + ": " + iR1.getRoom() + " <-> " + iR2.getRoom() + " (w "
166                    + iX2.variable().getName() + ", value:" + value() + ")";
167        }
168    }
169
170    protected static String toString(double[] x, double[] y) {
171        DecimalFormat df = new DecimalFormat("0.00");
172        StringBuffer s = new StringBuffer();
173        for (int i = 0; i < x.length; i++) {
174            if (i > 0)
175                s.append(",");
176            s.append(df.format(x[i] - y[i]));
177        }
178        return "[" + s.toString() + "]";
179    }
180
181    @Override
182    public double value() {
183        return iValue;
184    }
185}