input: def most_common(nums: List[int]) -> List[int]:
      """Designs an algorithm to find the most common elements in an array of integers.
  
      >>> most_common([3, 4, 1, 2, 5, 3, 3])
      [3]
      """
output:     frequency = {}
      for num in nums:
          if num in frequency:
              frequency[num] += 1
          else:
              frequency[num] = 1
      
      max_freq = max(frequency.values())
      most_common_elements = [num for num, freq in frequency.items() if freq == max_freq]
      
      return most_common_elements