Top K Frequent Words (LaiCode version)

class Solution { public: class compare{ public: bool operator()(pair<int, string> a, pair<int, string> b){ if (a.first < b.first) return true; else if (b.first < a.first) return false; else return a.second < b.second; } }; vector<string> topKFrequent(vector<string> combo, int k) { // write your solution here if (combo.empty()){ vector<string> res; return res; } // first construct a map unordered_map<string, int> m; // populate the map for (auto & c : combo) m[c]++; priority_queue< pair<int, string>, vector< pair<int, string> >, compare> pq; for (unordered_map<string, int>::iterator it = m.begin(); it != m.end(); it++){ pq.push(make_pair(it->second, it->first)); } vector<string> res; for (int i = 0; i < k; i++){ res.push_back(pq.top().second); pq.pop(); } return res; } };