NQueen.java

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

public class Main {

    public static void main(String[] args) throws Exception {
        Scanner scn = new Scanner (System.in);
        int n = scn.nextInt();
        int [][] chess = new int [n][n];
        printNQueens(chess, "", 0);
        
    }

    public static void printNQueens(int[][] chess, String qsf, int row) {
        if(row==chess.length){
            System.out.println(qsf+".");
            return;
        }
        
        for(int col=0; col<chess[0].length; col++){
             if(safe(chess,row,col)==true){
             chess[row][col]=1;
        
         printNQueens(chess,qsf+ row+"-"+col+", ", row+1);
         chess[row][col]=0;
            
        }
        }
        
    }
    
    public static boolean safe(int[][] chess,int row, int col){
        for(int i = row-1,j=col-1; i>=0 && j>=0; i--,j--){
          if  ( chess[i][j]==1){
             return false;
        }
            
        }
        
        for(int i = row-1,j=col; i>=0; i--){
          if  ( chess[i][j]==1){
             return false;
        
            
        }  
        }
        for(int i = row-1,j=col+1; i>=0 && j<chess[0].length; i--,j++){
          if  ( chess[i][j]==1){
             return false;
        }
            
        }
        return true;
    }
}