/*
* Copyright 2011 JBoss Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.drools.planner.examples.nqueens.domain.solution;
import org.apache.commons.lang.builder.CompareToBuilder;
import org.drools.planner.api.domain.entity.PlanningEntityDifficultyWeightFactory;
import org.drools.planner.core.solution.Solution;
import org.drools.planner.examples.nqueens.domain.NQueens;
import org.drools.planner.examples.nqueens.domain.Queen;
public class QueenDifficultyWeightFactory implements PlanningEntityDifficultyWeightFactory {
public Comparable createDifficultyWeight(Solution solution, Object planningEntity) {
NQueens nQueens = (NQueens) solution;
Queen queen = (Queen) planningEntity;
int distanceFromMiddle = calculateDistanceFromMiddle(nQueens.getN(), queen.getColumnIndex());
return new QueenDifficultyWeight(queen, distanceFromMiddle);
}
private static int calculateDistanceFromMiddle(int n, int columnIndex) {
int middle = n / 2;
int distanceFromMiddle = Math.abs(columnIndex - middle);
if ((n % 2 == 0) && (columnIndex < middle)) {
distanceFromMiddle--;
}
return distanceFromMiddle;
}
public static class QueenDifficultyWeight implements Comparable<QueenDifficultyWeight> {
private final Queen queen;
private final int distanceFromMiddle;
public QueenDifficultyWeight(Queen queen, int distanceFromMiddle) {
this.queen = queen;
this.distanceFromMiddle = distanceFromMiddle;
}
public int compareTo(QueenDifficultyWeight other) {
return new CompareToBuilder()
// The more difficult queens have a lower distance to the middle
.append(other.distanceFromMiddle, distanceFromMiddle) // Decreasing
.append(queen.getColumnIndex(), other.queen.getColumnIndex())
.toComparison();
}
}
}