# 66. Plus One

## 19 Dec 66. Plus One

You are given a large integer represented as an integer array `digits`, where each `digits[i]` is the `ith` digit of the integer. The digits are ordered from most significant to least significant in left-to-right order. The large integer does not contain any leading `0`‘s.

Increment the large integer by one and return the resulting array of digits.

Example 1:

```Input: digits = [1,2,3]
Output: [1,2,4]
Explanation: The array represents the integer 123.
Incrementing by one gives 123 + 1 = 124.
Thus, the result should be [1,2,4].
```

Example 2:

```Input: digits = [4,3,2,1]
Output: [4,3,2,2]
Explanation: The array represents the integer 4321.
Incrementing by one gives 4321 + 1 = 4322.
Thus, the result should be [4,3,2,2].
```

Example 3:

```Input: digits = [9]
Output: [1,0]
Explanation: The array represents the integer 9.
Incrementing by one gives 9 + 1 = 10.
Thus, the result should be [1,0].
```

Constraints:

• `1 <= digits.length <= 100`
• `0 <= digits[i] <= 9`
• `digits` does not contain any leading `0`‘s.

class Solution:
def plusOne(self, digits: List[int]) -> List[int]:
if digits[-1] < 9:
digits[-1] += 1
return digits
elif (len(digits) ==1 and digits[0] == 9):
return [1, 0]
else:
digits[-1]=0
digits[0:-1] = self.plusOne(digits[0:-1])
return digits