LeetCode 52. N-Queens II

https://leetcode.com/problems/n-queens-ii/

跟上一题完全一样啊

class Solution {
public:
    int totalNQueens(int n) {
        int ret = 0;
        for(int i=0;i<n;i++)
            vis[i] = 0;
        int pos[n];
        dfs(ret, pos, 0, n );
        return ret;
    }

    void dfs( int &ret, int pos[], int ptr, int n ) {
        if(ptr > n) return;
        if(ptr == n) {
            ret++;
            return;
        }
        for(int i=0;i<n;i++) {
            if(vis[i])continue;
            int flag = 1;
            for(int j=0;j<ptr;j++) {
                if(ptr-j == i-pos[j] || ptr-j == pos[j]-i ) {
                    flag = 0;
                    break;
                }
            }
            if(flag) {
                vis[i] = 1;
                pos[ptr] = i;
                dfs(ret, pos, ptr+1, n);
                vis[i] = 0;
            }
        }
    }

private:
    int vis[10001];
};