input: Write a function to find the third largest element in a given row. If the given row does not have at least three distinct elements, return None.
  def third_largest(lst):
      if len(lst) < 3:
          return None
      distinct = []
      for i in lst:
          if i not in distinct:
              distinct.append(i)
      if len(distinct) < 3:
          return None
      distinct.sort(reverse=True)
      return distinct[2]
  
  assert third_largest([12, 13, 13, 45, 22, 99])==22
  assert third_largest([3, 3, 3])==None
  assert third_largest([1, 2])==None
  assert third_largest([10, 20, 30, 40, 50])==30
  assert third_largest([5, 5, 5, 5, 5])==None
output: def third_largest(lst):
      if len(lst) < 3:
          return None
      distinct = []
      for i in lst:
          if i not in distinct:
              distinct.append(i)
      if len(distinct) < 3:
          return None
      distinct.sort(reverse=True)
      return distinct[2]