nqueens.cpp

#include<iostream>
#include<bits/stdc++.h>
using namespace std;

int board[20][20];

bool isPossible(int n, int row, int col){
 
    for(int i=row-1; i>=0; i--){
        if(board[i][col] == 1){
            return false;
        }
    }

    for(int i=row-1, j=col-1; i>=0 && j>=0 ; i--, j--){
        if(board[i][j] ==1){
            return false;
        }

    }

    
    for(int i=row-1,j=col+1;i>=0 && j<n; i--,j++){
        if(board[i][j] == 1){
            return false;
        }
    }

    return true;
}

void nQueenHelper(int n, int row){
    if(row==n){
       
        for(int i=0;i<n;i++){
            for(int j=0;j<n;j++){
                cout << board[i][j] << " ";
            }
            cout<<endl;
        }
        cout<<endl;
    }

    
    for(int j=0; j<n; j++){
        if(isPossible(n,row,j)){ 
            board[row][j] = 1;
            nQueenHelper(n,row+1);
            board[row][j] = 0;

        }
    }
    
    return;
}

void placeNQueens(int n){
    memset(board,0,11*11*sizeof(int));

    nQueenHelper(n,0);
}

int main(){
    int n;
    cout<<"Enter the Number of queens: "; 
    cin>>n;
    cout<<endl;
    placeNQueens(n);
    return 0;
}