LeetCode 49. Group Anagrams

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class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, vector<string>> m;
        for (string &s : strs) {
            string key = s;
            sort(key.begin(), key.end());
            m[key].emplace_back(s);
        }
        vector<vector<string>> ans(m.size());
        int i = 0;
        for (auto [_, s] : m)
            ans[i++] = move(s);
        return ans;
    }
};
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class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, vector<string>> m;
        for (string &s : strs) {
            m[strSort(s)].emplace_back(s);
        }
        vector<vector<string>> ans(m.size());
        int i = 0;
        for (auto [_, s] : m)
            ans[i++] = move(s);
        return ans;
    }
    string strSort(string &s) {
        int cnt[26] = {0};
        for (auto &c : s)
            ++cnt[c - 'a'];
        string ans;
        for (int i = 0; i < 26; i++)
            ans += string(cnt[i], i + 'a');
        return ans;
    }
};
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class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        unordered_map<string, vector<string>> m;
        for (string &s : strs) {
            m[strCnt(s)].emplace_back(s);
        }
        vector<vector<string>> ans(m.size());
        int i = 0;
        for (auto [_, s] : m)
            ans[i++] = move(s);
        return ans;
    }
    string strCnt(string &s) {
        int cnt[26] = {0};
        for (auto &c : s)
            ++cnt[c - 'a'];
        string ans;
        for (int i = 0; i < 26; i++)
            ans += (i + 'a') + cnt[i];
        return ans;
    }
};