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 = 0; 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] >= 0 ) {
                    result.push_back(strs[str_map[tmp]]);
                    str_map[tmp] = -1;
                }
            }
        }
        return result;
    }
};