class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        // 4、边界
        if (strs.empty()) {
            return vector<vector<string>>{};
        }
        // 1、将每个字母按字典序将字符排列一把
        vector<string> tempStrVec(strs.begin(), strs.end()); // 为了不改变原来的数组，因此新构造一个
        GetOrderedVec(tempStrVec);
        // 2、将字母丢到一个map表里面去，记录位置
        map<string, vector<int>> wordsMap;
        FindSameWordsPos(tempStrVec, wordsMap);
        // 3、遍历一把，存储起来
        vector<vector<string>> res;
        GetResult(strs, wordsMap, res);
        return res;
    }
    void GetOrderedVec(vector<string>& strs) {
        for (auto& words : strs) {
            sort(words.begin(), words.end());
        }
    }
    void FindSameWordsPos(const vector<string>& strs, map<string, vector<int>>& wordsMap) {
        for (int i = 0; i < strs.size(); ++i) {
            string words = strs[i];
            wordsMap[words].emplace_back(i);
        }
    }
    void GetResult(const vector<string>& strs, const map<string, vector<int>>& wordsMap, vector<vector<string>>& res) {
        for (auto& words : wordsMap) {
            vector<string> tempRes;
            for (const auto pos : words.second) {
                tempRes.emplace_back(strs[pos]);
            }
            res.emplace_back(tempRes);
        }
    };
};