1def top_k_frequent(nums, k):2    count = {}3    freq = [[] for i in range(len(nums) + 1)]45    for n in nums:6        count[n] = 1 + count.get(n, 0)78    for n, c in count.items():9        freq[c].append(n)1011    res = []12    for i in range(len(freq) - 1, 0, -1):13        for n in freq[i]:14            res.append(n)1516            if len(res) == k:17                return res