字符串“同素异形体”可以用key-value的unordered_map存储

49. Group Anagrams

Medium

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Given an array of strings, group anagrams together.

Example:

Input: ​​["eat", "tea", "tan", "ate", "nat", "bat"]​​, Output: [ ["ate","eat","tea"], ["nat","tan"], ["bat"] ]

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        vector<vector<string>> result;
        if (strs.empty()) { return result; }
        unordered_map<string, vector<string>> hashtable;
        for (string str : strs) {
            string tmp = str;
            sort(tmp.begin(), tmp.end());
            hashtable[tmp].push_back(str);//插入一个key为tmp，value为增加str的容器
        }
        for (unordered_map<string, vector<string>>::iterator i = hashtable.begin(); i != hashtable.end(); i++) {
            vector<string> sol(i->second.begin(), i->second.end());
            result.push_back(sol);
        }
        return result;
    }
};