queen.cpp

#include <iostream>
#include <string>

using namespace std;

int ans = 0;
bool takencols[8] , takendiag1[16], takendiag2[16];

void place(string board[8] , int r, int &ans) {
    if (r == 8) {
        ans++;
        return;
    }
    for (int c = 0; c < 8; c++) {
        if (board[r][c] == '.') {
            if (!takencols[c] && !takendiag1[r - c + 8 - 1] && !takendiag2[r + c]) {
                takencols[c] = takendiag1[r - c + 8 - 1] = takendiag2[r + c] = true;
                place(board, r + 1, ans);
                takencols[c] = takendiag1[r - c + 8 - 1] = takendiag2[r + c] = false;
            }
        }
    }
}

int main() {
    string b;
    string board[8];
    int ans = 0;
    for (int i = 0; i < 8; i++) {
        cin >> board[i];
    }
    place(board , 0, ans);
    cout << ans;
    return 0;
}