LC 49. Group Anagrams

https://leetcode.com/problems/group-anagrams/description/?envType=study-plan-v2&envId=top-interview-150

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, vector<string>> Map;
        for (auto &x: strs) {
            vector<int> cnt(26, 0);
            for (auto &y: x) cnt[y - 'a'] += 1;
            string str = "";
            for (auto &c: cnt) {
                if (c == 0) str += "000";
                else if (c < 10) str += "00" + to_string(c);
                else if (c < 100) str += "0" + to_string(c);
                else str += to_string(c);
            }
            Map[str].push_back(x);
        }
        vector<vector<string>> res;
        for (auto &x: Map) {
            res.push_back(x.second);
        }
        return res;
    }
};

Time Complexity: O(n)
Space: O(n)

先計算出每個單字的字母出現數量，再將數量轉換成字串放入 Map 中，最終就可以知道有那些組了。