001package net.sf.cpsolver.ifs.solution; 002 003import net.sf.cpsolver.ifs.model.Value; 004import net.sf.cpsolver.ifs.model.Variable; 005import net.sf.cpsolver.ifs.util.DataProperties; 006 007/** 008 * General implementation of solution comparator. <br> 009 * <br> 010 * The solution is better than the best ever found solution when it has more 011 * variables assigned. In the case, when both solutions have the same number of 012 * assigned variables, the better solution is the one with smaller total value, 013 * i.e., the sum of {@link net.sf.cpsolver.ifs.model.Value#toDouble()} over all 014 * assigned variables. 015 * 016 * @see Solution 017 * @see net.sf.cpsolver.ifs.solver.Solver 018 * 019 * @version IFS 1.2 (Iterative Forward Search)<br> 020 * Copyright (C) 2006 - 2010 Tomáš Müller<br> 021 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 022 * <a href="http://muller.unitime.org">http://muller.unitime.org</a><br> 023 * <br> 024 * This library is free software; you can redistribute it and/or modify 025 * it under the terms of the GNU Lesser General Public License as 026 * published by the Free Software Foundation; either version 3 of the 027 * License, or (at your option) any later version. <br> 028 * <br> 029 * This library is distributed in the hope that it will be useful, but 030 * WITHOUT ANY WARRANTY; without even the implied warranty of 031 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 032 * Lesser General Public License for more details. <br> 033 * <br> 034 * You should have received a copy of the GNU Lesser General Public 035 * License along with this library; if not see 036 * <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>. 037 */ 038public class GeneralSolutionComparator<V extends Variable<V, T>, T extends Value<V, T>> implements 039 SolutionComparator<V, T> { 040 041 public GeneralSolutionComparator() { 042 } 043 044 /** No parameters are used so far. */ 045 public GeneralSolutionComparator(DataProperties properties) { 046 } 047 048 @Override 049 public boolean isBetterThanBestSolution(Solution<V, T> currentSolution) { 050 if (currentSolution.getBestInfo() == null) 051 return true; 052 int unassigned = currentSolution.getModel().nrUnassignedVariables(); 053 if (currentSolution.getModel().getBestUnassignedVariables() != unassigned) 054 return currentSolution.getModel().getBestUnassignedVariables() > unassigned; 055 return currentSolution.getModel().getTotalValue() < currentSolution.getBestValue(); 056 } 057 058}