算法1

注意下双关键字排序

C++ 代码

typedef pair<int,string> PIS;
class Solution {
public:
    vector<string> topKFrequent(vector<string>& words, int k) {
        vector<string>ans(k);
        unordered_map<string,int>hash;
        for(auto &c : words)hash[c] ++;
        priority_queue<PIS>pq;
        for(auto &c : hash){
            pq.push({-c.second,c.first});
            if(pq.size() > k)pq.pop();
        }
        for(int i = k-1; i>= 0;--i){
            ans[i] = pq.top().second;
            pq.pop();
        }
        return ans;
    }
};