Anagrams [LeetCode]

Given an array of strings, return all groups of strings that are anagrams.

Note: All inputs will be in lower-case.

Summary: To sort and compare strings, using map to record distinct strings.

 class Solution {
 public:
     vector<string> anagrams(vector<string> &strs) {
         vector<string> result;
         map<string, int> str_map;
         for(int i = ; i < strs.size(); i ++) {
             string tmp = strs[i];
             std::sort(tmp.begin(), tmp.end());
             if(str_map.find(tmp) == str_map.end()) {
                 str_map[tmp] = i;
             }else {
                 result.push_back(strs[i]);
                 if(str_map[tmp] >=  ) {
                     result.push_back(strs[str_map[tmp]]);
                     str_map[tmp] = -;
                 }
             }
         }
         return result;
     }
 };