```
class Solution(object):
def plusOne(self, digits):
decent = 1
for i in range(1, len(digits)+1):
s = decent + digits[-i]
if s >= 10:
digits[-i] = s % 10
decent = 1
else:
digits[-i] = s
decent = 0
break
if decent == 1:
digits = [1] + digits
return digits
```