题解 | #字符串的排列# 10-29 NO 7 使用set去重是很聪明的想法

class Solution {
public:
    set<string>ret;
    void dfs(string str, int s) {
        if (s == str.size() - 1) {
            ret.insert(str);
            return;
        }
        for (int i = s; i < str.size(); i++) {
             swap(str[i], str[s]);
             dfs(str, s + 1);
             swap(str[i], str[s]);
        }
    }
    
    vector<string> Permutation(string str) {
        dfs(str, 0);
        vector<string>ret1;
        // 将set转为vector
        set<string>::iterator it;
        for (it = ret.begin(); it != ret.end(); it++) {
            ret1.push_back(*it);
        }
        return ret1;
    }
};