LeetCode 49. Group Anagrams

Given an array of strings, group anagrams together.

["eat", "tea", "tan", "ate", "nat", "bat"], 

Return:

[ ["ate", "eat","tea"], ["nat","tan"], ["bat"] ]

my initial answer:

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        set<char> charSet;
        vector<int> indexSet;
        map<set<char>,vector<int>> myMap;
        vector<vector<string>> result;
        vector<string> tempResult;
        for(int i = 0; i < strs.size(); i ++){
            string tempStr = strs[i];
            set<char> tempCharSet;
            vector<int> tempIndexSet;
            for(int j = 0; j < tempStr.size(); j ++){
                tempCharSet.insert(tempStr[i]);
            }
            map<set<char>,vector<int>>::iterator it = myMap.find(tempCharSet);
            if(it == myMap.end()){
                tempIndexSet.push_back(i);
                myMap.insert(make_pair(tempCharSet,tempIndexSet));
            }
            else ((*it).second).push_back(i);
        }
        map<set<char>,vector<int>>::iterator it = myMap.begin();
        while(it != myMap.end()){
            indexSet = (*it).second;
            for(int i = 0; i < indexSet.size(); i ++){
                tempResult.push_back(strs[i]);
            }
            result.push_back(tempResult);
            tempResult.clear();
            it ++;
        }
        return result;
    }
};

 但是在最长的那个case，超时了，后来看了别人的算法，改进了。

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string>& strs) {
        map<string,vector<string>> myMap;
        for(int i = 0; i < strs.size(); i ++){
            string temp = strs[i];
            sort(temp.begin(),temp.end());
            myMap[temp].push_back(strs[i]);
        }
        vector<vector<string>> result;
        
        map<string,vector<string>>::iterator it = myMap.begin();
        vector<string> temp;
        while(it != myMap.end()){
            temp = (*it).second;
            result.push_back(temp);
            it ++;
        }
        return result;
    }
};