input: Write a function to find the maximum sum of an array of non-negative integers that does not exceed a given upper limit. If the array is empty, return 0.
  assert findMaxSum(10, [1, 3, 5, 4, 2, 6])==10
  assert findMaxSum(20, [1, 3, 5, 4, 2, 6])==21
  assert findMaxSum(5, [1, 2, 3, 4, 5])==5
  assert findMaxSum(0, [1, 2, 3, 4, 5])==0
  assert findMaxSum(10, [])==0
output: def findMaxSum(upper_limit, arr):
      arr.sort(reverse=True)
      current_sum = 0
      for num in arr:
          if current_sum + num <= upper_limit:
              current_sum += num
          else:
              break
      return current_sum