import java.util.Arrays;
public class EightQueens {
public static void solveNQueens() {
int[] queenPos = new int[8];
Arrays.fill(queenPos, -1);
placeQueen(queenPos, 0);
}
private static void placeQueen(int[] queenPos, int row) {
if (row == 8) {
printSolution(queenPos);
return;
}
for (int col = 0; col < 8; col++) {
if (isValid(queenPos, row, col)) {
queenPos[row] = col;
placeQueen(queenPos, row + 1);
queenPos[row] = -1;
}
}
}
private static boolean isValid(int[] queenPos, int row, int col) {
for (int i = 0; i < row; i++) {
if (queenPos[i] == col || Math.abs(i - row) == Math.abs(queenPos[i] - col)) {
return false;
}
}
return true;
}
private static void printSolution(int[] queenPos) {
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
if (queenPos[i] == j) {
System.out.print("Q ");
} else {
System.out.print("* ");
}
}
System.out.println();
}
System.out.println();
}
public static void main(String[] args) {
solveNQueens();
}
}