题目：

题解：

class Solution {
public:vector<vector<string>> groupAnagrams(vector<string>& strs) {// 自定义对 array<int, 26> 类型的哈希函数auto arrayHash = [fn = hash<int>{}] (const array<int, 26>& arr) -> size_t {return accumulate(arr.begin(), arr.end(), 0u, [&](size_t acc, int num) {return (acc << 1) ^ fn(num);});};unordered_map<array<int, 26>, vector<string>, decltype(arrayHash)> mp(0, arrayHash);for (string& str: strs) {array<int, 26> counts{};int length = str.length();for (int i = 0; i < length; ++i) {counts[str[i] - 'a'] ++;}mp[counts].emplace_back(str);}vector<vector<string>> ans;for (auto it = mp.begin(); it != mp.end(); ++it) {ans.emplace_back(it->second);}return ans;}
};