class Solution {
public:
    vector<int> topKFrequent(vector<int>& nums, int k) {
        std::unordered_map<int, int> m;
        for(int n : nums) {
            m[n]++;
        }

        std::priority_queue<int, std::vector<int>, std::function<bool(int,int)>>
        q([&m](int a, int b){
            return m[a] > m[b];
        });

        for(auto& [n,_] : m) {
            q.push(n);
            if (q.size() > k) {
                q.pop();
            }
        }
        vector<int> res(q.size());
        std::copy(&(q.top()), &(q.top()) + q.size(), &res[0]);
        return res;
    }
};