class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, vector<string>> table;
        for (int i = 0; i < strs.size(); i++) {
            int count[26] = {0};
            for (char c: strs[i]) {
                count[c - 'a']++;
            }
            string key = "";
            for (int j = 0; j < 26; j++) {
                key += to_string(count[j]);
            }
            auto it = table.find(key);
            if (it == table.end()) {
                table.insert({key, vector<string>()});
                it = table.find(key);
            }
            it->second.push_back(strs[i]);
        }
        vector<vector<string>> res;
        for (auto it = table.begin(); it != table.end(); it++){
            res.push_back(it->second);
        }
        return res;
    }
};