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Open-source constraint solver.
/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2020, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
package org.chocosolver.solver.search.loop;
import org.chocosolver.solver.Model;
import org.chocosolver.solver.Solver;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.propagation.PropagationEngine;
import org.chocosolver.solver.search.strategy.decision.Decision;
import org.chocosolver.solver.search.strategy.strategy.AbstractStrategy;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.util.ESat;
import java.util.Arrays;
import static org.chocosolver.solver.search.strategy.Search.inputOrderLBSearch;
/**
* A list of service, just for fun
* Created by cprudhom on 09/10/15.
* Project: choco.
*/
class RecursiveSearchLoop {
RecursiveSearchLoop() {
}
public static int dfs(Model model, AbstractStrategy strategy) {
// some preprocess for the first call
int c = 0;
try {
model.getSolver().getEngine().propagate();
} catch (ContradictionException e) {
return c;
}
Decision dec = strategy.getDecision();
if (dec != null) {
// apply the decision
model.getEnvironment().worldPush();
try {
dec.buildNext();
dec.apply();
c += dfs(model, strategy);
} catch (ContradictionException cex) {
model.getSolver().getEngine().flush();
}
model.getEnvironment().worldPop();
model.getEnvironment().worldPush();
try {
dec.buildNext();
dec.apply();
c += dfs(model, strategy);
} catch (ContradictionException cex) {
model.getSolver().getEngine().flush();
}
model.getEnvironment().worldPop();
} else {
assert model.getSolver().isSatisfied() == ESat.TRUE;
c++;
System.out.printf("Solution: %s\n", Arrays.toString(model.getVars()));
}
return c;
}
public static int lds(Model model, AbstractStrategy strategy, int dis) {
int c = 0;
try {
model.getSolver().getEngine().propagate();
} catch (ContradictionException e) {
return c;
}
Decision dec = strategy.getDecision();
if (dec != null) {
// apply the decision
model.getEnvironment().worldPush();
try {
dec.buildNext();
dec.apply();
c += lds(model, strategy, dis);
} catch (ContradictionException cex) {
model.getSolver().getEngine().flush();
}
model.getEnvironment().worldPop();
if (dis > 0) {
model.getEnvironment().worldPush();
try {
dec.buildNext();
dec.apply();
c += lds(model, strategy, dis - 1);
} catch (ContradictionException cex) {
model.getSolver().getEngine().flush();
}
model.getEnvironment().worldPop();
}
} else {
assert model.getSolver().isSatisfied() == ESat.TRUE;
c++;
System.out.printf("Solution: %s\n", Arrays.toString(model.getVars()));
}
return c;
}
public static int dds(Model model, AbstractStrategy strategy, int dis, int dep) {
int c = 0;
try {
model.getSolver().getEngine().propagate();
} catch (ContradictionException e) {
return c;
}
Decision dec = strategy.getDecision();
if (dec != null) {
// apply the decision
if (dep >= dis) {
model.getEnvironment().worldPush();
try {
dec.buildNext();
dec.apply();
c += ilds(model, strategy, dis, dep - 1);
} catch (ContradictionException cex) {
model.getSolver().getEngine().flush();
}
model.getEnvironment().worldPop();
} else {
dec.buildNext();
}
if (dis > 0) {
model.getEnvironment().worldPush();
try {
dec.buildNext();
dec.apply();
c += ilds(model, strategy, dis - 1, dep);
} catch (ContradictionException cex) {
model.getSolver().getEngine().flush();
}
model.getEnvironment().worldPop();
}
} else if (dis == 0) {
assert model.getSolver().isSatisfied() == ESat.TRUE;
c++;
System.out.printf("Solution: %s\n", Arrays.toString(model.getVars()));
}
return c;
}
public static int ilds(Model model, AbstractStrategy strategy, int dis, int dep) {
int c = 0;
try {
model.getSolver().getEngine().propagate();
} catch (ContradictionException e) {
return c;
}
Decision dec = strategy.getDecision();
if (dec != null) {
// apply the decision
if (dep >= dis) {
model.getEnvironment().worldPush();
try {
dec.buildNext();
dec.apply();
c += ilds(model, strategy, dis, dep - 1);
} catch (ContradictionException cex) {
model.getSolver().getEngine().flush();
}
model.getEnvironment().worldPop();
} else {
dec.buildNext();
}
if (dis > 0) {
model.getEnvironment().worldPush();
try {
dec.buildNext();
dec.apply();
c += ilds(model, strategy, dis - 1, dep);
} catch (ContradictionException cex) {
model.getSolver().getEngine().flush();
}
model.getEnvironment().worldPop();
}
} else if (dis == 0) {
assert model.getSolver().isSatisfied() == ESat.TRUE;
c++;
System.out.printf("Solution: %s\n", Arrays.toString(model.getVars()));
}
return c;
}
public static void main(String[] args) {
Model model = new Model();
IntVar[] X = model.intVarArray("X", 3, 0, 2, false);
// model.post(solver.allDifferent(X));
Solver r = model.getSolver();
r.setEngine(new PropagationEngine(model));
r.getEngine().initialize();
// System.out.printf("%d solutions\n", setDFS(solver, ISF.lexico_LB(X)));
System.out.printf("%d solutions\n", lds(model, inputOrderLBSearch(X), 3));
// for (int d = 2; d < 3; d++) {
// System.out.printf("%d solutions\n", ilds(solver, ISF.lexico_LB(X), d, X.length));
// }
}
}