null created by NightZpy - https://repl.it/NsLs/1

SumOneToIntArray.py

import time

def add_one (data, last_pos):
  last = data[last_pos]
  if last < 9:
    data[last_pos] = data[last_pos] + 1
    return data
  
  if last_pos >= 0:
    if last == 9:
      data[last_pos] = 0
      if last_pos == 0:
        data.insert(0, 1)
      else:
        add_one (data, last_pos - 1)
  return data

def add_one_itr (data):
  idx = len(data) - 1
  while idx >= 0:
    num = data[idx]
    if num < 9:
      data[idx] = data[idx] + 1
      return data
    if num == 9:
      data[idx] = 0
      if idx == 0:
        data.insert(0, 1)
    idx = idx - 1
  return data
  
data = [0,0,0,0]  
start = time.time()
print add_one(data, len(data) - 1)
end = time.time()
print end - start
data = [0,0,0,0]
start = time.time()
print add_one_itr(data)
end = time.time()
print end - start