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*
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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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*/
package samples.integer;
import org.kohsuke.args4j.Option;
import org.slf4j.LoggerFactory;
import samples.AbstractProblem;
import solver.ResolutionPolicy;
import solver.Solver;
import solver.constraints.IntConstraintFactory;
import solver.search.strategy.IntStrategyFactory;
import solver.variables.BoolVar;
import solver.variables.IntVar;
import solver.variables.VariableFactory;
import util.tools.StringUtils;
import static solver.constraints.IntConstraintFactory.*;
import static solver.constraints.LogicalConstraintFactory.ifThenElse;
/**
* <a href="http://www.gecode.org">gecode</a>:<br/>
* "A group of people wants to take a group photo. Each person can give
* preferences next to whom he or she wants to be placed on the
* photo. The problem to be solved is to find a placement that
* violates as few preferences as possible."
* <br/>
*
* @author Charles Prud'homme
* @since 03/08/11
*/
public class Photo extends AbstractProblem {
@Option(name = "-d", aliases = "--data", usage = "Photo preferences .", required = false)
Data data = Data.small;
IntVar[] positions;
IntVar[] dist;
BoolVar[] viols;
IntVar violations;
@Override
public void createSolver() {
solver = new Solver("Photo");
}
@Override
public void buildModel() {
positions = VariableFactory.boundedArray("pos", data.people(), 0, data.people() - 1, solver);
violations = VariableFactory.bounded("viol", 0, data.preferences().length, solver);
viols = VariableFactory.boolArray("b", data.prefPerPeople(), solver);
dist = new IntVar[data.prefPerPeople()];
for (int i = 0; i < data.prefPerPeople(); i++) {
int pa = data.preferences()[(2 * i)];
int pb = data.preferences()[2 * i + 1];
IntVar k = VariableFactory.bounded(StringUtils.randomName(),-20000,20000,solver);
solver.post(IntConstraintFactory.sum(new IntVar[]{positions[pb], k}, positions[pa]));
dist[i] = VariableFactory.abs(k);
solver.post(
ifThenElse(viols[i],
arithm(dist[i], ">", 1),
arithm(dist[i], "<=", 1)));
}
solver.post(sum(viols, violations));
solver.post(alldifferent(positions, "BC"));
solver.post(arithm(positions[1], ">", positions[0]));
}
@Override
public void configureSearch() {
solver.set(IntStrategyFactory.minDom_LB(positions));
}
@Override
public void solve() {
solver.findOptimalSolution(ResolutionPolicy.MINIMIZE, violations);
// solver.findAllSolutions();
}
@Override
public void prettyOut() {
LoggerFactory.getLogger("bench").info("Photo -- {}", data.name());
StringBuilder st = new StringBuilder();
st.append("\tPositions: ");
for (int i = 0; i < data.people(); i++) {
st.append(String.format("%d ", positions[i].getValue()));
}
st.append(String.format("\n\tViolations: %d", violations.getValue()));
LoggerFactory.getLogger("bench").info(st.toString());
}
public static void main(String[] args) {
new Photo().execute(args);
}
/////////////////////////////////// DATA //////////////////////////////////////////////////
static enum Data {
small {
@Override
int[] preferences() {
return new int[]{
0, 2,
1, 4,
2, 3,
2, 4,
3, 0,
4, 3,
4, 0,
4, 1
};
}
@Override
int people() {
return 5;
}
@Override
int prefPerPeople() {
return 8;
}
},
large {
@Override
int[] preferences() {
return new int[]{
0, 2, 0, 4, 0, 7, 1, 4, 1, 8, 2, 3, 2, 4, 3, 0, 3, 4,
4, 5, 4, 0, 5, 0, 5, 8, 6, 2, 6, 7, 7, 8, 7, 6
};
}
@Override
int people() {
return 9;
}
@Override
int prefPerPeople() {
return 17;
}
};
abstract int[] preferences();
abstract int people();
abstract int prefPerPeople();
}
}