#include "000库函数.h"

 //使用回溯法

 class Solution {

 public:

     int totalNQueens(int n) {

         int res = ;

         vector<int>x(n, -);//标记

         NQueue(x, res, );

         return res;

     }

     void NQueue(vector<int>&x, int &num, int row) {

         int n = x.size();

         if (n == row)

             num++;

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

             if (Danger(x, row, col)) {

                 x[row] = col;

                 NQueue(x, num, row + );

                 x[row] = -;//回溯

             }

     }

     bool Danger(vector<int>x, int row, int col) {

         for (int i = ; i < row; ++i)

             if (col == x[i] || abs(row - i) == abs(x[i] - col))

                 //行列与斜边

                 return false;

         return true;

     }

 };

 void T052() {

     Solution s;

     cout << s.totalNQueens() << endl;

     cout << s.totalNQueens() << endl;

 }