vector<string> anagrams(vector<string> &strs) {

if (strs.empty()) return vector<string>();

map<string, vector<string> > hashmap;

for (size_t i = 0; i < strs.size(); ++i) {

string sortedStr = strs[i];

std::sort(sortedStr.begin(), sortedStr.end());

hashmap[sortedStr].push_back(strs[i]);

}

//iterate over the hash table and get output

vector<string> ret;

map<string, vector<string> >::iterator iter = hashmap.begin();

for (; iter != hashmap.end(); ++iter) {

if (iter->second.size() > 1) {

for (size_t i = 0; i < iter->second.size(); ++i) {

ret.push_back(iter->second[i]);

}

}

}

return ret;

}