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 = 0;
        vector<int>x(n, -1);//标记
        NQueue(x, res, 0);
        return res;
    }

    void NQueue(vector<int>&x, int &num, int row) {
        int n = x.size();
        if (n == row)
            num++;
        for (int col = 0; col < n; ++col) 
            if (Danger(x, row, col)) {
                x[row] = col;
                NQueue(x, num, row + 1);
                x[row] = -1;//回溯
            }        
    }

    bool Danger(vector<int>x, int row, int col) {
        for (int i = 0; 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(4) << endl;
    cout << s.totalNQueens(8) << endl;
}