692

class Solution {
public:
    vector<string> topKFrequent(vector<string>& words, int k) {
        unordered_map<string, int> freq;
        for(auto w : words)
            freq[w]++;

        priority_queue<pair<int, string>> pq;

        for(auto w: freq){
            pq.push({-w.second, w.first});
            if(pq.size()>k) pq.pop();
        }

        vector<string> res;
        while(!pq.empty()){
            res.push_back(pq.top().second);
            pq.pop();
        }
        reverse(res.begin(), res.end());
        return res;
    }
};