Top K Frequent Elements

class Solution:
    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
        N = len(nums)
        freq = defaultdict(int)
        bucket = defaultdict(set)

        for x in nums:
            freq[x] += 1

        for key, value in freq.items():
            bucket[value].add(key)

        answer = []
        for i in range(N + 1, 0, -1):
            for x in bucket[i]:
                if len(answer) == k:
                    break
                answer.append(x)
            if len(answer) == k:
                break

        return answer