347. Top K Frequent Elements [Medium]

class Solution {
    public int[] topKFrequent(int[] nums, int k) {
        int[] res = new int[k];
        PriorityQueue> q = new PriorityQueue<>((a, b) -> {
            return b.getValue() - a.getValue();
        });
        HashMap map = new HashMap<>();
        for (int i : nums) {
            map.put(i, map.getOrDefault(i, 0) + 1);
        }
        for (Map.Entry entry : map.entrySet()) {
            q.offer(entry);
        }
        for (int i = 0; i < res.length; i++) {
            res[i] = q.poll().getKey();
        }
        return res;
    }
}