/**
* Copyright (c) 1999-2014, Ecole des Mines de Nantes
* All rights reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the Ecole des Mines de Nantes nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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*/
package solver.constraints.nary.nValue.amnv.rules;
import solver.constraints.Propagator;
import solver.constraints.nary.nValue.amnv.mis.F;
import solver.exception.ContradictionException;
import solver.variables.IntVar;
import util.objects.graphs.UndirectedGraph;
import java.util.BitSet;
/**
* R2 filtering rule (back-propagation)
*
* @since 01/01/2014
* @author Jean-Guillaume Fages
*/
public class R2 implements R {
private BitSet valInMIS;
public void filter(IntVar[] vars, UndirectedGraph graph, F heur, Propagator aCause) throws ContradictionException{
int n = vars.length-1;
BitSet mis = heur.getMIS();
if(mis.cardinality()==vars[n].getUB()){
if(valInMIS == null) valInMIS = new BitSet();
valInMIS.clear();
for (int i = mis.nextSetBit(0); i >= 0; i = mis.nextSetBit(i + 1)) {
int ub = vars[i].getUB();
for (int k = vars[i].getLB(); k <= ub; k = vars[i].nextValue(k)) {
valInMIS.set(k);
}
}
for (int i = mis.nextClearBit(0); i < n; i = mis.nextClearBit(i + 1)) {
int ub = vars[i].getUB();
for (int k = vars[i].getLB(); k <= ub; k = vars[i].nextValue(k)) {
if (!valInMIS.get(k)) {
vars[i].removeValue(k, aCause);
}
}
}
}
}
}