力扣算法题—052N皇后问题2

跟前面的N皇后问题没区别，还更简单

 #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;
 }