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Open-source constraint solver.
/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2022, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
/**
* Created by IntelliJ IDEA.
* User: Jean-Guillaume Fages
* Date: 14/01/13
* Time: 16:36
*/
package org.chocosolver.solver.constraints.set;
import org.chocosolver.solver.constraints.Propagator;
import org.chocosolver.solver.constraints.PropagatorPriority;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.SetVar;
import org.chocosolver.solver.variables.Variable;
import org.chocosolver.solver.variables.events.IntEventType;
import org.chocosolver.solver.variables.events.SetEventType;
import org.chocosolver.util.ESat;
import org.chocosolver.util.objects.setDataStructures.ISetIterator;
/**
* Sums elements given by a set variable
*
* @author Jean-Guillaume Fages
*/
public class PropSumOfElements extends Propagator {
//***********************************************************************************
// VARIABLES
//***********************************************************************************
private final IntVar sum;
private final SetVar set;
private final int offSet;
private final int[] weights;
//***********************************************************************************
// CONSTRUCTOR
//***********************************************************************************
/**
* Sums elements given by a set variable:
*
* if(weights !=null){
* SUM(weights[i-offset] | i in setVar) = sum
* (also ensures indexes is a subset of [offset, offset+weights.length-1])
* }else{
* SUM(i | i in setVar) = sum
* }
*
* @param setVar a set variable
* @param weights array of int (can be null to sum the indexes)
* @param offset offset to access array cells (0 in Java, 1 in MiniZinc)
* @param sum integer variable representing the sum over the set
*/
public PropSumOfElements(SetVar setVar, int[] weights, int offset, IntVar sum) {
super(new Variable[]{setVar, sum}, PropagatorPriority.BINARY, false);
this.sum = (IntVar) vars[1];
this.set = (SetVar) vars[0];
this.weights = weights;
this.offSet = offset;
}
//***********************************************************************************
// METHODS
//***********************************************************************************
@Override
public int getPropagationConditions(int vIdx) {
if (vIdx == 0) return SetEventType.all();
else return IntEventType.boundAndInst();
}
@Override
public void propagate(int evtmask) throws ContradictionException {
int lbSum = 0;
int ubPosSum = 0;
int ubNegSum = 0;
ISetIterator iter = set.getUB().iterator();
while (iter.hasNext()){
int j = iter.nextInt();
if(outOfScope(j)){
set.remove(j,this);
}else {
if (set.getLB().contains(j)) {
lbSum += get(j);
} else if (get(j) >= 0) {
ubPosSum += get(j);
} else {
ubNegSum += get(j);
}
}
}
int min = lbSum+ubNegSum;
int max = lbSum+ubPosSum;
sum.updateBounds(min, max, this);
// filter set
int lb = sum.getLB();
int ub = sum.getUB();
if (lb == min && ub == max) {
return;
}
iter = set.getUB().iterator();
while (iter.hasNext()){
int j = iter.nextInt();
if (!set.getLB().contains(j)) {
if (min + get(j) > ub) {
if (set.remove(j, this)) {
// weights[j] is positive
ubPosSum -= get(j);
}
} else {
if (max + get(j) < lb) {
if (set.remove(j, this)) {
// weights[j] is negative
ubNegSum -= get(j);
}
} else {
if (max - get(j) < lb || min - get(j) > ub) {
if (set.force(j, this)) {
// weight[j] is positive
lbSum += get(j);
}
}
}
}
}
}
min = lbSum + ubNegSum;
max = lbSum + ubPosSum;
sum.updateBounds(min, max, this);
}
private boolean outOfScope(int j){
return weights!=null && (j=offSet+weights.length);
}
private int get(int j) {
return (weights == null) ? j : weights[j - offSet];
}
@Override
public ESat isEntailed() {
int lbSum = 0;
int ubPosSum = 0;
int ubNegSum = 0;
ISetIterator iter = set.getUB().iterator();
while (iter.hasNext()){
int j = iter.nextInt();
if(set.getLB().contains(j)){
if(outOfScope(j)){
return ESat.FALSE;
}
lbSum += get(j);
}else if(!outOfScope(j)) {
if (get(j) >= 0) {
ubPosSum += get(j);
} else {
ubNegSum += get(j);
}
}
}
int min = lbSum+ubNegSum;
int max = lbSum+ubPosSum;
if(sum.getLB()>max || sum.getUB()