// Copyright 2011 Hakan Kjellerstrand hakank@gmail.com
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//
// Unless required by applicable law or agreed to in writing, software
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and

import java.io.*;
import java.util.*;
import java.text.*;

public class NQueens {

static {
}

/**
*
* Solves the N Queens problem.
*
*/
private static void solve(int n, int num, int print) {

Solver solver = new Solver("NQueens");

System.out.println("n: " + n);

//
// variables
//
IntVar[] q = solver.makeIntVarArray(n, 0, n-1, "q");

//
// constraints
//

IntVar b = solver.makeIntVar(1, 1, "b");
IntVar[] q1 = new IntVar[n];
IntVar[] q2 = new IntVar[n];
for(int i = 0; i < n; i++) {
for(int j = 0; j < i; j++) {
// // q[i]+i != q[j]+j
solver.makeNonEquality(
solver.makeSum(q[i],i).Var(),
solver.makeSum(q[j],j).Var()));

// q[i]-i != q[j]-j
solver.makeNonEquality(solver.makeSum(q[i],-i).Var(),
solver.makeSum(q[j],-j).Var()));
}
}

//
// Solve
//
DecisionBuilder db = solver.makePhase(q,
solver.CHOOSE_MIN_SIZE_LOWEST_MAX,
solver.ASSIGN_CENTER_VALUE);
solver.newSearch(db);
int c = 0;
while (solver.nextSolution()) {
if (print != 0) {
for(int i = 0; i < n; i++) {
System.out.print(q[i].value() + " ");
}
System.out.println();
}
c++;
if (num > 0 && c >= num) {
break;
}
}
solver.endSearch();

// Statistics
System.out.println();
System.out.println("Solutions: " + solver.solutions());
System.out.println("Failures: " + solver.failures());
System.out.println("Branches: " + solver.branches());
System.out.println("Wall time: " + solver.wall_time() + "ms");

}

public static void main(String[] args) throws Exception {
int n = 8;
int num = 0;
int print = 1;

if (args.length > 0) {
n = Integer.parseInt(args[0]);
}

if (args.length > 1) {
num = Integer.parseInt(args[1]);
}

if (args.length > 2) {
print = Integer.parseInt(args[2]);
}

NQueens.solve(n, num, print);
}
}