public class EightQueen {

private final int COUNT = 8;

private int [][] matrix;

private int numOfResult = 0;

public EightQueen(){

matrix = new int[8][8];

numOfResult = 0;

}

private void printResult() {

numOfResult++;

System.out.println("Result " + numOfResult + " :");

printArray();

}

private void printArray(){

System.out.println("**********************");

for (int i = 0; i < COUNT; i++) {

for (int j = 0; j < COUNT; j++) {

System.out.print(matrix[i][j]);

}

System.out.println("");

}

System.out.println("**********************");

}

private boolean check(int row, int col) {

int i, j;

// can not be the same column

i = row - 1;

while (i >=0) {

if(matrix[i][col] == 1) {

return false;

}

i--;

}

// can not be the same diagnal

i = row - 1;

j = col - 1;

while (i >= 0 && j >= 0) {

if (matrix[i][j] == 1) {

return false;

}

i--;

j--;

}

i = row - 1;

j = col + 1;

while (i >= 0 && j < COUNT) {

if (matrix[i][j] == 1) {

return false;

}

i--;

j++;

}

return true;

}

public void solve(int row) {

for(int i = 0; i <COUNT; i++){// try on all columns

matrix[row][i] = 1;

if (check(row, i)) {

if (row == COUNT - 1) {

printResult();

} else {

solve(row+1);

}

}

matrix[row][i] = 0;//roll back

}

}

}