My Solution For Digit Sum (Still buggy) for Practice 8/21/2014

digit.py

def buildDigits(digit_list):

	# sort the digit list
	# TODO: Here's where the bug is. Because the 0's get pushed to the front of the list, I put 0's at the beginning of numbers.
	# What would need to happen is potentially a sort, and then pushing 0's back in the list a couple spaces?
	digit_list.sort(reverse = True)

	summands = ['', '']

  # Here's the basic idea for the algorithm: Sort the digits, then divide them equally (in sorted order) among two strings 
  # that you build. Ideally you want the lowest digits to the left, since they minimize the value of the sum (hence the sort).
  # For cases with an odd number of digits, just put the first digit in the first bin. That seems to work (but I'm not
  # exactly sure why... Any ideas?

	if len(digit_list) % 2 is 1:
		summands[0] = digit_list.pop()

	summand_to_add_to = 0
	while len(digit_list) > 0:
	  # concat the new digit onto the end of the current bin
		summands[ summand_to_add_to ] = summands[ summand_to_add_to ] + digit_list.pop()

    # Swap between bin 0 and 1
		summand_to_add_to = (summand_to_add_to + 1) % 2

  # convert them to integers and return the sum
	return sum(map(int, summands))

# This is case I'm failing on. I'm not handling those zeros correctly.
print(buildDigits([ '0', '1', '2', '3', '4', '0', '1', '2', '3' ]))

# My algorithm for parsing input woudl be simple (this part is untested): Read the line, convert all to integers:
while True:
  digit_count, digits = map(int, input().strip().split())
  if digit_count is 0:
    break
  
  print(buildDigits(digits))