LeetCode 52. N皇后II

$n皇后问题$

class Solution {
public:
    int res;
    int N;          
    vectorcol;
    vectordg;
    vectorudg;
    vectorg; 
    void dfs(int u){
        if(u == N){
            res++;
            return;
        }
        else
        for(int i = 0; i < N; i++){
            if(!col[i] && !dg[u+i] && !udg[N-u+i]){
                col[i] = dg[u+i] = udg[N-u+i] = 1;
                g[u][i] = 'Q';
                dfs(u+1);
                col[i] = dg[u+i] = udg[N-u+i] = 0;
                g[u][i] = '.';
            }

        }
    }
    int totalNQueens(int n) {
        N = n;
        col.resize(n, 0);
        dg.resize(2*n, 0);
        udg.resize(2*n, 0);
        g.resize(n);
        for(int i = 0; i < n; i++)
            for(int j = 0; j < n; j++)
            {
                g[i].resize(n);
                g[i][j] = '.';
            }
        dfs(0);

        return res;
    }
};

作者：陈平安
链接：https://www.acwing.com/activity/content/code/content/2060907/
来源：AcWing
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