001package org.cpsolver.ifs.solution; 002 003import org.cpsolver.ifs.assignment.Assignment; 004import org.cpsolver.ifs.model.Value; 005import org.cpsolver.ifs.model.Variable; 006import org.cpsolver.ifs.util.DataProperties; 007 008/** 009 * General implementation of solution comparator. <br> 010 * <br> 011 * The solution is better than the best ever found solution when it has more 012 * variables assigned. In the case, when both solutions have the same number of 013 * assigned variables, the better solution is the one with smaller total value, 014 * i.e., the sum of {@link org.cpsolver.ifs.model.Value#toDouble(Assignment)} over all 015 * assigned variables. 016 * 017 * @see Solution 018 * @see org.cpsolver.ifs.solver.Solver 019 * 020 * @version IFS 1.3 (Iterative Forward Search)<br> 021 * Copyright (C) 2006 - 2014 Tomáš Müller<br> 022 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 023 * <a href="http://muller.unitime.org">http://muller.unitime.org</a><br> 024 * <br> 025 * This library is free software; you can redistribute it and/or modify 026 * it under the terms of the GNU Lesser General Public License as 027 * published by the Free Software Foundation; either version 3 of the 028 * License, or (at your option) any later version. <br> 029 * <br> 030 * This library is distributed in the hope that it will be useful, but 031 * WITHOUT ANY WARRANTY; without even the implied warranty of 032 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 033 * Lesser General Public License for more details. <br> 034 * <br> 035 * You should have received a copy of the GNU Lesser General Public 036 * License along with this library; if not see 037 * <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>. 038 * 039 * @param <V> Variable 040 * @param <T> Value 041 */ 042public class GeneralSolutionComparator<V extends Variable<V, T>, T extends Value<V, T>> implements SolutionComparator<V, T> { 043 044 public GeneralSolutionComparator() { 045 } 046 047 /** No parameters are used so far. 048 * @param properties solver configuration 049 **/ 050 public GeneralSolutionComparator(DataProperties properties) { 051 } 052 053 @Override 054 public boolean isBetterThanBestSolution(Solution<V, T> currentSolution) { 055 if (currentSolution.getBestInfo() == null) 056 return true; 057 int unassigned = currentSolution.getAssignment().nrUnassignedVariables(currentSolution.getModel()); 058 if (currentSolution.getModel().getBestUnassignedVariables() != unassigned) 059 return currentSolution.getModel().getBestUnassignedVariables() > unassigned; 060 return currentSolution.getModel().getTotalValue(currentSolution.getAssignment()) < currentSolution.getModel().getBestValue(); 061 } 062 063}