1 /*******************************************************************************
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2008 Daniel Le Berre
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 *******************************************************************************/
28 package org.sat4j.minisat.orders;
29
30 import static org.sat4j.core.LiteralsUtils.neg;
31 import static org.sat4j.core.LiteralsUtils.var;
32
33 import java.util.ArrayList;
34 import java.util.Collections;
35 import java.util.List;
36
37 import org.sat4j.minisat.core.ILits2;
38
39 /**
40 * @author leberre To change the template for this generated type comment go to
41 * Window>Preferences>Java>Code Generation>Code and Comments
42 */
43 public class MyOrder extends VarOrder<ILits2> {
44
45 private static final long serialVersionUID = 1L;
46
47 /*
48 * (non-Javadoc)
49 *
50 * @see org.sat4j.minisat.IHeuristics#init()
51 */
52 @Override
53 public void init() {
54 super.init();
55 List<ValuedLit> v = new ArrayList<ValuedLit>(order.length);
56 int id;
57 for (int i = 1; i < order.length; i++) {
58 id = order[i];
59 v.add(new ValuedLit(id,lits.nBinaryClauses(id) + lits.nBinaryClauses(neg(id))));
60 }
61 Collections.sort(v);
62 // System.out.println(v);
63 for (int i = 0; i < v.size(); i++) {
64 ValuedLit t = v.get(i);
65 order[i + 1] = t.id;
66 int index = var(t.id);
67 varpos[index] = i + 1;
68 }
69 lastVar = 1;
70 }
71
72 @Override
73 public String toString() {
74 return "Init VSIDS order with binary clause occurrences."; //$NON-NLS-1$
75 }
76 }