692. Top K Frequent Words

class Solution {
typedef pair<string, int> tp;
public:
    struct cmp {
        bool operator()(const tp &a, const tp &b) const{
            if(a.second < b.second) return true;
            else if(a.second == b.second) {
                int t = strcmp(a.first.c_str(), b.first.c_str());
                if(t < 0) return false;
                else return true;
            } else {
                return false;
            }
        }
    };

    vector<string> topKFrequent(vector<string>& words, int k) {
        unordered_map<string, int> wtf;
        vector<string> res;
        for(auto w: words) {
            if(wtf[w]) wtf[w]++;
            else wtf[w] = 1;
        }

        priority_queue<tp, vector<tp>, cmp> pq;

        for(auto i = wtf.begin(); i != wtf.end(); i++) {
            pq.push(make_pair(i->first, i->second));
        }

        for(int i = 0; i < k; i++) {
            res.push_back(pq.top().first);
            pq.pop();
        }
        return res;
    }
};