LeetCode 347. Top K Frequent Elements

 1 public class Solution {
 2     public List<Integer> topKFrequent(int[] nums, int k) {
 3         Map<Integer, Integer> map = new HashMap<>();
 4         Arrays.stream(nums).forEach(x -> map.merge (x, 1, Integer::sum));
 5         Queue<Integer> queue = new PriorityQueue<>((x, y) -> map.get(x).compareTo(map.get(y)));
 6         map.forEach((key,value) ->{
 7             if (queue.size()<k) {
 8                 queue.add(key);
 9             }
10             else if (map.get(queue.peek())<value){
11                 queue.poll();
12                 queue.add(key);
13             }
14         });
15         List<Integer> list = new ArrayList<>();
16         queue.forEach(list::add);
17         return list;
18     }
19 }