nqueen_brute.cpp

#include<iostream>
using namespace std;

bool canPlace(int board[][10], int n, int x, int y) {

	//Column
	for (int k = 0; k < x; k++) {
		if (board[k][y] == 1) {
			return false;
		}
	}
	//Left Diag
	int i = x, j = y;
	while (i >= 0 and j >= 0) {
		if (board[i][j] == 1) {
			return false;
		}
		i--; j--;
	}

	//Right Diag
	i = x, j = y;
	while (i >= 0 and j < n) {
		if (board[i][j] == 1) {
			return false;
		}
		i--; j++;
	}
	return true;
}


int NQueen(int n, int board[][10], int i) {
	//Base Case
	if (i == n) {
		//Print the board
		return 1;
	}
	//Rec Case
	//Try to place queen at every column/position in the current row
	int cnt = 0;

	for (int j = 0; j < n; j++) {
		if (canPlace(board, n, i, j)) {
			board[i][j] = 1;
			cnt += NQueen(n, board, i + 1);
			board[i][j] = 0;
		}
	}
	return cnt;
}

int main() {

	int board[10][10] = {0};
	int n;
	cin >> n;

	cout << NQueen(n, board, 0);

	return 0;
}