Sword To Offer 027 - 字符串的排列

class Solution {
public:
    vector<string> Permutation(string str) {
        vector<string> res;
        if(str == "")
            return res;
        do {
            res.push_back(str);
        } while(next_permutation(str.begin(), str.end()));
        return res;
    }
};