class Solution {
public:
    /**
     * 
     * @param strs string字符串vector the strings
     * @return string字符串
     */
    static bool cmp(string &a, string &b) {
        return (a + b) < (b + a);
    }
    string minString(vector<string>& strs) {
        sort(strs.begin(), strs.end(), cmp);
        string ret;
        for (auto n : strs) {
            ret += n;
        }
        return ret;
    }
};