input: Write a function to determine the mean and median of an array. The function should return the mean and median as a tuple. If the given array is empty then return (0, 0).
  def mean_median(arr):
      if len(arr) == 0:
          return (0, 0)
      arr_sum = 0
      for i in range(len(arr)):
          arr_sum += arr[i]
      mean = arr_sum / len(arr)
      arr = sorted(arr)
      if len(arr) % 2 != 0:
          median = arr[len(arr) // 2]
      else:
          median = (arr[len(arr) // 2] + arr[len(arr) // 2 - 1]) / 2
      return mean, median
  assert mean_median([10, 15, 20, 25, 30, 35]) == (22.5, 22.5)
  assert mean_median([1, 2, 3, 4, 5]) == (3.0, 3)
  assert mean_median([1]) == (1.0, 1)
  assert mean_median([]) == (0, 0)
output: def mean_median(arr):
      if len(arr) == 0:
          return (0, 0)
      arr_sum = 0
      for i in range(len(arr)):
          arr_sum += arr[i]
      mean = arr_sum / len(arr)
      arr = sorted(arr)
      if len(arr) % 2 != 0:
          median = arr[len(arr) // 2]
      else:
          median = (arr[len(arr) // 2] + arr[len(arr) // 2 - 1]) / 2
      return mean, median