49.cpp

// sort_hash.cpp
class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, int> map;
        vector<vector<string>> res;
        for (int i = 0, count = 0; i < strs.size(); ++i) {
            string newstr = strs[i];
            ranges::sort(newstr);
            auto it = map.find(newstr);
            if (it == map.end()) {
                map[newstr] = count++;
                res.push_back({strs[i]});
            } else {
                res[it->second].push_back(strs[i]);
            }
        }
        return res;
    }
};
// encode
class Solution2 {
    string encode(const string& s) {
        string res(26, 0);
        for (char c : s) {
            ++res[c - 'a'];
        }
        return res;
    }

public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, vector<string>> mp;
        for (auto& s : strs) {
            mp[encode(s)].push_back(s);
        }
        vector<vector<string>> res;
        for (auto& [k, v] : mp) {
            res.push_back(move(v));
        }
        return res;
    }
};