Day-17 Top K Frequent Elements

class Solution {
    public int[] topKFrequent(int[] nums, int k) {
        HashMap<Integer,Integer> map=new HashMap<>();
        
        for(int i:nums){
            map.put(i,map.get(i)==null?1:map.get(i)+1);
        }
        
    PriorityQueue<Integer> heap =
            new PriorityQueue<Integer>((n1, n2) -> map.get(n1) - map.get(n2));

    for (int n: map.keySet()) {
      heap.add(n);
      if (heap.size() > k)
        heap.poll();
    }

    int[] top_k =new int[heap.size()];
        int i=heap.size()-1;
    while (!heap.isEmpty())
      top_k[i--]=heap.poll();
    return top_k;
    }
}