Given an array of strings, return all groups of strings that are anagrams. Note: All inputs will be in lower-case.

anagramsStr.cc

class Solution {
public:
    vector<string> anagrams(vector<string> &strs) {
        // find distribution or sort
        vector<string> res;
        int n = strs.size();
        // sort each string in string array
        // use hash to find equal elements of two arrays or duplicate elements in one array
        unordered_map<string, int> dict;
        for(int i = 0; i<n; ++i)
        {
            string s = strs[i];
            sort(s.begin(), s.end());
            if(dict.find(s) == dict.end()) // new 
            {
                dict.insert(make_pair(s, i));
            }else
            {
                if(dict[s]>=0)
                {
                    res.push_back(strs[dict[s]]);
                    dict[s] = -1;
                }
                res.push_back(strs[i]);
            }
        }
        return res;
    }
};