刷题：https://leetcode-cn.com/problems/top-k-frequent-elements/submissions/
前 K 个高频元素collections.Counter(nums)
class Solution:
def topKFrequent(self, nums: List[int], k: int) -> List[int]:
co = collections.Counter(nums)
tmp = co.most_common(k)
res = []
for i in tmp:
res.append(i[0])
return res