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

 1 #include "000库函数.h"
 2 
 3 //使用回溯法
 4 class Solution {
 5 public:
 6     int totalNQueens(int n) {
 7         int res = 0;
 8         vector<int>x(n, -1);//标记
 9         NQueue(x, res, 0);
10         return res;
11     }
12 
13     void NQueue(vector<int>&x, int &num, int row) {
14         int n = x.size();
15         if (n == row)
16             num++;
17         for (int col = 0; col < n; ++col) 
18             if (Danger(x, row, col)) {
19                 x[row] = col;
20                 NQueue(x, num, row + 1);
21                 x[row] = -1;//回溯
22             }        
23     }
24 
25     bool Danger(vector<int>x, int row, int col) {
26         for (int i = 0; i < row; ++i)
27             if (col == x[i] || abs(row - i) == abs(x[i] - col))
28                 //行列与斜边
29                 return false;
30         return true;
31     }
32 };
33 
34 void T052() {
35     Solution s;
36     cout << s.totalNQueens(4) << endl;
37     cout << s.totalNQueens(8) << endl;
38 }