PlusOne.py

# https://leetcode.com/problems/plus-one/description/
'''
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]:
        carry = 1
        for i in range(len(digits)-1, -1, -1):
            sum = digits[i] + carry 
            if sum >= 10:
                carry = 1
                digits[i] = 0
            else:
                digits[i] = sum
                carry = 0
                break

        if carry > 0:
            digits.insert(0, carry)
        return digits 

if __name__ == "__main__":
    s = Solution()
    print(s.plusOne([4,5,6,7]))
    print(s.plusOne([3,9,9,9]))
    print(s.plusOne([3,9,8,9]))
    print(s.plusOne([9,9,9,9]))
    print(s.plusOne([9]))
    print(s.plusOne([0]))