topKfreq.c

class Solution {
public:
    vector<int> topKFrequent(vector<int>& nums, int k) {
        vector<int> ret;
        priority_queue <unsigned long long>  q; 
        unordered_map <int, int> h;
        for (int i = 0; i< nums.size(); i++) {
            h[nums[i]] = h[nums[i]]+1;
        }

        for(auto it = h.begin(); it!=h.end(); it++) {
            q.push((it->first & 0xffffffff) | ((unsigned long long)it->second << 32));
        }

        for(int i = 0; i<k; i++) {
            int x = q.top() & 0xffffffff;
            q.pop();
            ret.push_back(x);
        }
        return ret;
    }
};