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* 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
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/**
* Created by IntelliJ IDEA.
* User: Jean-Guillaume Fages
* Date: 21/06/12
* Time: 19:07
*/
package solver.constraints.nary;
import gnu.trove.map.hash.THashMap;
import solver.Solver;
import solver.constraints.Propagator;
import solver.constraints.PropagatorPriority;
import solver.exception.ContradictionException;
import solver.variables.IntVar;
import solver.variables.events.IntEventType;
import solver.variables.events.PropagatorEventType;
import util.ESat;
import util.tools.ArrayUtils;
import java.util.BitSet;
/**
* !redundant propagator!
*/
public class PropKnapsack extends Propagator<IntVar> {
//***********************************************************************************
// VARIABLES
//***********************************************************************************
private int[] weigth, energy, order;
private double[] ratio;
private int n;
private IntVar capacity, power;
//***********************************************************************************
// CONSTRUCTORS
//***********************************************************************************
public PropKnapsack(IntVar[] itemOccurence, IntVar capacity, IntVar power,
int[] weight, int[] energy) {
super(ArrayUtils.append(itemOccurence, new IntVar[]{capacity, power}), PropagatorPriority.LINEAR, true);
this.weigth = weight;
this.energy = energy;
this.n = itemOccurence.length;
this.capacity = vars[n];
this.power = vars[n + 1];
this.order = new int[n];
this.ratio = new double[n];
for (int i = 0; i < n; i++) {
ratio[i] = (double) (energy[i]) / (double) (weight[i]);
}// sort (could be improved)
BitSet in = new BitSet(n);
double best = -1;
int index = 0;
for (int i = 0; i < n; i++) {
int item = -1;
for (int o = in.nextClearBit(0); o < n; o = in.nextClearBit(o + 1)) {
if (item == -1 || ratio[o] > best) {
best = ratio[o];
item = o;
}
}
in.set(item);
if (item == -1) {
throw new UnsupportedOperationException();
} else {
order[index++] = item;
}
}
}
//***********************************************************************************
// METHODS
//***********************************************************************************
@Override
public int getPropagationConditions(int vIdx) {
return IntEventType.boundAndInst();
}
@Override
public void propagate(int evtmask) throws ContradictionException {
double camax = capacity.getUB();
double pomin = 0;
for (int i = 0; i < n; i++) {
camax -= weigth[i] * vars[i].getLB();
pomin += energy[i] * vars[i].getLB();
}
power.updateLowerBound((int) pomin, aCause);
if (camax == 0) {
power.updateUpperBound((int) pomin, aCause);
} else if (camax < 0) {
contradiction(capacity, "");
} else {
int idx;
for (int i = 0; i < n; i++) {
if (camax < 0) {
throw new UnsupportedOperationException(camax + " < 0");
}
idx = order[i];
int delta = weigth[idx] * (vars[idx].getUB() - vars[idx].getLB());
if (delta > 0) {
if (delta <= camax) {
pomin += energy[idx] * (vars[idx].getUB() - vars[idx].getLB());
camax -= delta;
if (camax == 0) {
power.updateUpperBound((int) pomin, aCause);
return;
}
} else {
pomin += Math.ceil(camax * ratio[idx]);
power.updateUpperBound((int) pomin, aCause);
return;
}
}
}
}
}
@Override
public void propagate(int idxVarInProp, int mask) throws ContradictionException {
forcePropagate(PropagatorEventType.CUSTOM_PROPAGATION);
}
@Override
public ESat isEntailed() {
double camax = capacity.getUB();
double pomin = 0;
for (int i = 0; i < n; i++) {
camax -= weigth[i] * vars[i].getLB();
pomin += energy[i] * vars[i].getLB();
}
if (camax < 0 || pomin > power.getUB()) {
return ESat.FALSE;
}
if (isCompletelyInstantiated()) {
if (pomin == power.getValue()) {
return ESat.TRUE;
}
}
return ESat.UNDEFINED;
}
@Override
public void duplicate(Solver solver, THashMap<Object, Object> identitymap) {
if (!identitymap.containsKey(this)) {
int size = this.vars.length - 2;
IntVar[] aVars = new IntVar[size];
for (int i = 0; i < size; i++) {
this.vars[i].duplicate(solver, identitymap);
aVars[i] = (IntVar) identitymap.get(this.vars[i]);
}
this.vars[size].duplicate(solver, identitymap);
IntVar C = (IntVar) identitymap.get(this.vars[size]);
this.vars[size + 1].duplicate(solver, identitymap);
IntVar E = (IntVar) identitymap.get(this.vars[size + 1]);
identitymap.put(this, new PropKnapsack(aVars, C, E, this.weigth, this.energy));
}
}
}