class Solution:
    # Method to sort the array based on frequency
    def frequencySort(self, nums):
        from collections import Counter

        freq = Counter(nums)

        buckets = [[] for _ in range(max(freq.values()))] # create k buckets

        for num in freq: # populate buckets (0-based)

            buckets[freq[num]-1].append(num) 

        sorted_arr = []

        for i in range(len(buckets)): # worst case: O(N*log(N))

            if len(buckets[i])>1: # more then one number with the same freq.

                buckets[i].sort(reverse=True)

                for j in range(len(buckets[i])):

                    tmp_list = []
                    tmp_list.append(buckets[i][j])

                    sorted_arr.extend(tmp_list*(i+1))

            else:

                    sorted_arr.extend(buckets[i]*(i+1))

        return sorted_arr