CodeForces-Solutions/nqueen.cpp at main · vishalk11019/CodeForces-Solutions · GitHub

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#include<iostream>
using namespace std;


bool isSafe(int** arr, int x, int y, int n){

    for(int row=0; row<x; row++){
        if( arr[row][y] == 1 ){
            return false;
        }
    }

    int row=x;
    int col=y;

    while(row>=0 && col>=0){
        if( arr[row][col] == 1 ){
            return false;
        }
        row--;
        col--;
    }

    row=x;
    col=y;

    while(row>=0 && col<n){
        if( arr[row][col] == 1 ){
            return false;
        }
        row--;
        col++;
    }

    return true;
}

bool nqueen(int** arr, int x, int n){

    if(x>=n){
        return true;
    }

    for(int col=0; col<n; col++){

        if( isSafe(arr,x,col,n) ){

            arr[x][col]=1;

            if( nqueen(arr,x+1,n) ){
                return true;
            }

            arr[x][col]=0; // backtrack
        }
    }

    return false;
}

int main(){

    int n;
    cin>>n;

    int** arr = new int*[n];
    for(int i=0; i<n; i++){
        arr[i] = new int[n];
        for (int j=0; j<n; j++){
            arr[i][j]=0;
        }
    }

    if(nqueen(arr,0,n)){
        for(int i=0; i<n; i++){
            for (int j=0; j<n; j++){
                cout<<arr[i][j]<<" ";
            }
            cout<<endl;
        }
    }

    return 0;
}