topKfrequentNums.py

def topKFrequent(nums: List[int], k: int) -> List[int]:
        freq_by_num = {}
        max_freq = float("-inf")
        for num in nums:
            freq_by_num[num] = freq_by_num[num] + 1 if num in freq_by_num else 1
            max_freq = max(max_freq, freq_by_num[num])
            
        nums_by_freq = {}
        for num, freq in freq_by_num.items():
            nums_by_freq[freq] = nums_by_freq[freq] + [num] if freq in nums_by_freq else [num]
        return [j for i in range(max_freq+1) if i in nums_by_freq for j in nums_by_freq[i]][-k:]