LeetCode 347. 前 K 个高频元素 (map和priority_queue的使用)

class Solution {
public:
    vector<int> topKFrequent(vector<int>& nums, int k) {
        unordered_map<int,int> count;
        priority_queue<pair<int,int>> pq;
        vector<int> ans;
        for(int x:nums){
            count[x]++;
        }
        for(auto it:count){
            pq.push(make_pair(it.second,it.first));
        }
        while(k--){
            pair<int,int> p = pq.top();
            pq.pop();
            ans.push_back(p.second);
        }
        return ans;
    }
};