001package org.cpsolver.studentsct.heuristics.selection; 002 003import java.util.ArrayList; 004import java.util.Collections; 005import java.util.LinkedList; 006import java.util.List; 007 008import org.cpsolver.ifs.solver.Solver; 009import org.cpsolver.ifs.util.DataProperties; 010import org.cpsolver.ifs.util.Progress; 011import org.cpsolver.studentsct.heuristics.RandomizedBacktrackNeighbourSelection; 012import org.cpsolver.studentsct.model.Enrollment; 013import org.cpsolver.studentsct.model.Request; 014 015/** 016 * Use backtrack neighbour selection. For all unassigned variables (in a random 017 * order) that are marked as critical, {@link RandomizedBacktrackNeighbourSelection} is being used. 018 * 019 * <br> 020 * <br> 021 * 022 * @version StudentSct 1.3 (Student Sectioning)<br> 023 * Copyright (C) 2007 - 2014 Tomas Muller<br> 024 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 025 * <a href="http://muller.unitime.org">http://muller.unitime.org</a><br> 026 * <br> 027 * This library is free software; you can redistribute it and/or modify 028 * it under the terms of the GNU Lesser General Public License as 029 * published by the Free Software Foundation; either version 3 of the 030 * License, or (at your option) any later version. <br> 031 * <br> 032 * This library is distributed in the hope that it will be useful, but 033 * WITHOUT ANY WARRANTY; without even the implied warranty of 034 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 035 * Lesser General Public License for more details. <br> 036 * <br> 037 * You should have received a copy of the GNU Lesser General Public 038 * License along with this library; if not see 039 * <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>. 040 */ 041public class CriticalBacktrackSelection extends BacktrackSelection { 042 043 public CriticalBacktrackSelection(DataProperties properties) { 044 super(properties); 045 iIncludeAssignedRequests = properties.getPropertyBoolean("Neighbour.IncludeCriticalAssignedRequests", iIncludeAssignedRequests); 046 } 047 048 @Override 049 public void init(Solver<Request, Enrollment> solver, String name) { 050 List<Request> variables = new ArrayList<Request>(); 051 for (Request r: (iIncludeAssignedRequests ? solver.currentSolution().getModel().variables() : solver.currentSolution().getModel().unassignedVariables(solver.currentSolution().getAssignment()))) 052 if (r.isCritical()) variables.add(r); 053 Collections.shuffle(variables); 054 iRequests = new LinkedList<Request>(variables); 055 if (iRBtNSel == null) { 056 try { 057 iRBtNSel = new RandomizedBacktrackNeighbourSelection(solver.getProperties()); 058 iRBtNSel.init(solver); 059 } catch (Exception e) { 060 throw new RuntimeException(e.getMessage(), e); 061 } 062 } 063 Progress.getInstance(solver.currentSolution().getModel()).setPhase("Backtracking (critical)...", variables.size()); 064 } 065 066}