/*
* Copyright 2012 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.optaplanner.examples.nqueens.app;
import java.util.List;
import org.optaplanner.core.api.solver.Solver;
import org.optaplanner.core.api.solver.SolverFactory;
import org.optaplanner.examples.nqueens.domain.NQueens;
import org.optaplanner.examples.nqueens.domain.Queen;
import org.optaplanner.examples.nqueens.persistence.NQueensGenerator;
public class NQueensHelloWorld {
public static void main(String[] args) {
// Build the Solver
SolverFactory solverFactory = SolverFactory.createFromXmlResource(
"org/optaplanner/examples/nqueens/solver/nqueensSolverConfig.xml");
Solver solver = solverFactory.buildSolver();
// Load a problem with 8 queens
NQueens unsolved8Queens = new NQueensGenerator().createNQueens(8);
// Solve the problem
solver.solve(unsolved8Queens);
NQueens solved8Queens = (NQueens) solver.getBestSolution();
// Display the result
System.out.println("\nSolved 8 queens:\n" + toDisplayString(solved8Queens));
}
public static String toDisplayString(NQueens nQueens) {
StringBuilder displayString = new StringBuilder();
int n = nQueens.getN();
List<Queen> queenList = nQueens.getQueenList();
for (int row = 0; row < n; row++) {
for (int column = 0; column < n; column++) {
Queen queen = queenList.get(column);
if (queen.getColumn().getIndex() != column) {
throw new IllegalStateException("The queenList is not in the expected order.");
}
displayString.append(" ");
if (queen.getRow() != null && queen.getRow().getIndex() == row) {
displayString.append("Q");
} else {
displayString.append("_");
}
}
displayString.append("\n");
}
return displayString.toString();
}
}