415. Add Strings

https://leetcode.com/problems/add-strings/

Python

class Solution:
    def addStrings(self, num1: str, num2: str) -> str:
        result = []
        carry = 0

        string1 = list(num1)
        string2 = list(num2)

        while string1 or string2:
            char1 = string1.pop() if string1 else '0'
            char2 = string2.pop() if string2 else '0'

            n1 = ord(char1) - ord('0')
            n2 = ord(char2) - ord('0')

            value = n1 + n2 + carry
            carry = value // 10
            result.append(value % 10)

        if carry:
            result.append(carry)

        return ''.join([str(char) for char in result[::-1]])