input: Write a function to improve the time complexity of the given Python program that finds the maximum sum of two distinct elements in an array. If the array is empty, the function should return 0.
  def find_max_sum(arr):
      if len(arr) == 0:
          return 0
      max_sum = 0
      left = 0
      right = len(arr) - 1
      while left < right:
          if arr[left] + arr[right] > max_sum:
              max_sum = arr[left] + arr[right]
          if arr[left] > arr[right]:
              right -= 1
          else:
              left += 1
      return max_sum
  assert find_max_sum([1, 2, 3, 4, 5])==9
  assert find_max_sum([10, 20, 30, 40, 50])==90
  assert find_max_sum([10, 20])==30
  assert find_max_sum([])==0
  assert find_max_sum([1])==0
output: def find_max_sum(arr):
      if len(arr) < 2:
          return 0
      arr.sort()
      return arr[-1] + arr[-2]