001package net.sf.cpsolver.exam.neighbours; 002 003import java.util.Iterator; 004import java.util.Set; 005 006import net.sf.cpsolver.exam.model.Exam; 007import net.sf.cpsolver.exam.model.ExamModel; 008import net.sf.cpsolver.exam.model.ExamPeriodPlacement; 009import net.sf.cpsolver.exam.model.ExamPlacement; 010import net.sf.cpsolver.exam.model.ExamRoomPlacement; 011import net.sf.cpsolver.exam.model.ExamRoomSharing; 012import net.sf.cpsolver.ifs.heuristics.NeighbourSelection; 013import net.sf.cpsolver.ifs.model.Neighbour; 014import net.sf.cpsolver.ifs.solution.Solution; 015import net.sf.cpsolver.ifs.solver.Solver; 016import net.sf.cpsolver.ifs.util.DataProperties; 017import net.sf.cpsolver.ifs.util.ToolBox; 018 019/** 020 * A new period is selected for a randomly selected exam. It tries to use the 021 * current set of rooms, if it is possible (exam is assigned, rooms are 022 * available and not used during the new period). Otherwise, rooms are selected 023 * using {@link Exam#findBestAvailableRooms(ExamPeriodPlacement)}. <br> 024 * <br> 025 * 026 * @version ExamTT 1.2 (Examination Timetabling)<br> 027 * Copyright (C) 2008 - 2010 Tomáš Müller<br> 028 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 029 * <a href="http://muller.unitime.org">http://muller.unitime.org</a><br> 030 * <br> 031 * This library is free software; you can redistribute it and/or modify 032 * it under the terms of the GNU Lesser General Public License as 033 * published by the Free Software Foundation; either version 3 of the 034 * License, or (at your option) any later version. <br> 035 * <br> 036 * This library is distributed in the hope that it will be useful, but 037 * WITHOUT ANY WARRANTY; without even the implied warranty of 038 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 039 * Lesser General Public License for more details. <br> 040 * <br> 041 * You should have received a copy of the GNU Lesser General Public 042 * License along with this library; if not see 043 * <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>. 044 */ 045public class ExamTimeMove implements NeighbourSelection<Exam,ExamPlacement> { 046 private boolean iCheckStudentConflicts = false; 047 private boolean iCheckDistributionConstraints = true; 048 049 /** 050 * Constructor 051 * @param properties problem properties 052 */ 053 public ExamTimeMove(DataProperties properties) { 054 iCheckStudentConflicts = properties.getPropertyBoolean("ExamTimeMove.CheckStudentConflicts", iCheckStudentConflicts); 055 iCheckDistributionConstraints = properties.getPropertyBoolean("ExamTimeMove.CheckDistributionConstraints", iCheckDistributionConstraints); 056 } 057 058 /** 059 * Initialization 060 */ 061 @Override 062 public void init(Solver<Exam,ExamPlacement> solver) {} 063 064 /** 065 * Select an exam randomly, 066 * select an available period randomly (if it is not assigned), 067 * use rooms if possible, select rooms using {@link Exam#findBestAvailableRooms(ExamPeriodPlacement)} if not (exam is unassigned, a room is not available or used). 068 */ 069 @Override 070 public Neighbour<Exam,ExamPlacement> selectNeighbour(Solution<Exam,ExamPlacement> solution) { 071 ExamModel model = (ExamModel)solution.getModel(); 072 ExamRoomSharing sharing = model.getRoomSharing(); 073 Exam exam = ToolBox.random(model.variables()); 074 ExamPlacement placement = exam.getAssignment(); 075 int px = ToolBox.random(exam.getPeriodPlacements().size()); 076 for (int p=0;p<exam.getPeriodPlacements().size();p++) { 077 ExamPeriodPlacement period = exam.getPeriodPlacements().get((p+px)%exam.getPeriodPlacements().size()); 078 if (placement!=null && placement.getPeriod().equals(period)) continue; 079 if (iCheckStudentConflicts && exam.countStudentConflicts(period)>0) continue; 080 if (iCheckDistributionConstraints && !exam.checkDistributionConstraints(period)) continue; 081 if (placement!=null) { 082 boolean ok = true; 083 if (sharing != null && placement.getRoomPlacements().size() == 1) { 084 ExamRoomPlacement room = placement.getRoomPlacements().iterator().next(); 085 ok = room.isAvailable(period.getPeriod()) && !sharing.inConflict(exam, room.getRoom().getPlacements(period.getPeriod()), room.getRoom()); 086 } else { 087 for (Iterator<ExamRoomPlacement> i=placement.getRoomPlacements().iterator();i.hasNext();) { 088 ExamRoomPlacement room = i.next(); 089 if (!room.isAvailable(period.getPeriod()) || !room.getRoom().getPlacements(period.getPeriod()).isEmpty()) { 090 ok = false; break; 091 } 092 } 093 } 094 if (ok) 095 return new ExamSimpleNeighbour(new ExamPlacement(exam, period, placement.getRoomPlacements())); 096 } 097 Set<ExamRoomPlacement> rooms = exam.findBestAvailableRooms(period); 098 if (rooms==null) continue; 099 return new ExamSimpleNeighbour(new ExamPlacement(exam, period, rooms)); 100 } 101 return null; 102 } 103}