input: Write a python function to split an array into two parts where the sum of the first part is as close as possible to half the total sum.
  assert split_array_sum([1, 2, 3, 4, 5, 6]) == ([1, 2, 3, 4], [5, 6])
  assert split_array_sum([10, 20, 30, 40, 50]) == ([10, 20, 30], [40, 50])
  assert split_array_sum([5, 5, 5, 5, 5, 5]) == ([5, 5, 5], [5, 5, 5])
output: def split_array_sum(arr):
      total_sum = sum(arr)
      half_sum = total_sum / 2
      current_sum = 0
      first_part = []
      for num in arr:
          if current_sum + num <= half_sum:
              first_part.append(num)
              current_sum += num
          else:
              break
      second_part = arr[len(first_part):]
      return (first_part, second_part)