class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, vector<string>> data;
        for(const auto &s : strs){
            auto key = s;
            sort(key.begin(), key.end());
            data[key].push_back(s);
        }
        vector<vector<string>> ret;
        for(const auto &line : data){
            ret.push_back(line.second);
        }
        return ret;
    }
};