LeetCoder_____ N皇后 II(52)

1. 思路

和N皇后1问题类似，深度搜索，记录个数即可

2. 代码

class Solution {
public:
    int totalNQueens(int n) {
        vector<bool> vis1(n), vis2(2*n), vis3(2*n);
        int ret = 0;
        dfs(ret, 0, n, vis1, vis2, vis3);
        return ret;
    }

    void dfs(int& ret, int cur,int n, vector<bool>& vis1, vector<bool>& vis2, vector<bool>& vis3)
    {
        if(cur == n)
        {
            ret ++;
            return;
        }
        for(int i = 0; i < n; ++i)
        {
            if(vis1[i] || vis2[cur + i] || vis3[cur - i + n]) continue;
            vis1[i] = vis2[cur + i] = vis3[cur - i + n] = true;
            dfs(ret, cur + 1, n, vis1, vis2, vis3);
            vis1[i] = vis2[cur + i] = vis3[cur - i + n] = false;
        }


    }
};