八皇后问题及其推广

package nqueen;

/**
* Created by kai_li on 2016/1/25.
*/
public class NQueen {
static int NQUEEN = 8;
final static int SIZE = NQUEEN;
static int COUNT = 0;
static int[] cols = new int[SIZE] ;

public static void place(int n) {
for (int i = 0; i < SIZE; i++) {
boolean compatible = compatible(n, i);
if (compatible) {
cols
= i;
if (n == SIZE - 1) {
printSolution();
COUNT ++;
return;
} else {
place(n + 1);
}
} else {
continue;
}
}
}

public static void printSolution() {
for (int col : cols) {
System.out.print(col);
}
System.out.println();
return;
}

public static boolean compatible(int rowIndex, int val) {
for (int i = 0; i < rowIndex; i++) {
if (cols[i] == val) {
return false;
}
if (rowIndex - i == val - cols[i] ) {
return false;
}
if (rowIndex - i == cols[i] - val) {
return false;
}
}
return true;
}

public static void main(String[] args) {
place(0);
System.out.println(COUNT);
}
}