0347-top-k-frequent-elements.py

class Solution:
    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
        count = {}
        freq = [[] for i in range(len(nums) + 1)]

        for n in nums:
            count[n] = 1 + count.get(n, 0)
        for n, c in count.items():
            freq[c].append(n)

        res = []
        for i in range(len(freq) - 1, 0, -1):
            res += freq[i]
            if len(res) == k:
                return res
                

        # O(n)