1 /*******************************************************************************
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004, 2012 Artois University and CNRS
3 *
4 * All rights reserved. This program and the accompanying materials
5 * are made available under the terms of the Eclipse Public License v1.0
6 * which accompanies this distribution, and is available at
7 * http://www.eclipse.org/legal/epl-v10.html
8 *
9 * Alternatively, the contents of this file may be used under the terms of
10 * either the GNU Lesser General Public License Version 2.1 or later (the
11 * "LGPL"), in which case the provisions of the LGPL are applicable instead
12 * of those above. If you wish to allow use of your version of this file only
13 * under the terms of the LGPL, and not to allow others to use your version of
14 * this file under the terms of the EPL, indicate your decision by deleting
15 * the provisions above and replace them with the notice and other provisions
16 * required by the LGPL. If you do not delete the provisions above, a recipient
17 * may use your version of this file under the terms of the EPL or the LGPL.
18 *
19 * Based on the original MiniSat specification from:
20 *
21 * An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
22 * Sixth International Conference on Theory and Applications of Satisfiability
23 * Testing, LNCS 2919, pp 502-518, 2003.
24 *
25 * See www.minisat.se for the original solver in C++.
26 *
27 * Contributors:
28 * CRIL - initial API and implementation
29 *******************************************************************************/
30 package org.sat4j.minisat.core;
31
32 import java.io.Serializable;
33 import java.util.Comparator;
34
35 /**
36 * Utility class to sort the constraints according to their activity.
37 *
38 * @author daniel
39 *
40 */
41 public class ActivityComparator implements Comparator<Constr>, Serializable {
42
43 private static final long serialVersionUID = 1L;
44
45 /*
46 * (non-Javadoc)
47 *
48 * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
49 */
50 public int compare(Constr c1, Constr c2) {
51 long delta = Math.round(c1.getActivity() - c2.getActivity());
52 if (delta == 0) {
53 return c1.size() - c2.size();
54 }
55 return (int) delta;
56 }
57 }