(Leetcode) 347 - Top K Frequent Elements 풀이

public int[] topKFrequent(int[] nums, int k) {
    Map<Integer, Integer> counter = new HashMap<>();

    Arrays.stream(nums)
            .forEach(num -> counter.merge(num, 1, Integer::sum));

    return counter.entrySet().stream()
            .sorted(Map.Entry.<Integer, Integer>comparingByValue().reversed())
            .mapToInt(Map.Entry::getKey)
            .limit(k)
            .toArray();
}