692. Top K Frequent Words

https://leetcode.com/problems/top-k-frequent-words/description/

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>> q;
        
        for (auto & f : freq)
        {
            q.push({-f.second, f.first});
            if (q.size() > k)
                q.pop();
        }
        
        vector<string> res;
        while (!q.empty())
        {
            res.push_back(q.top().second);
            q.pop();
        }
        
        reverse(res.begin(), res.end());
        
        return res;
    }
};