Multiply Strings Python Solution with Tests

lcpy gen -n 43   # by problem number
lcpy gen -s multiply_strings   # by problem name

Input: num1 = "2", num2 = "3"
Output: "6"

Input: num1 = "123", num2 = "456"
Output: "56088"

class Solution:
    # Time: O(m * n)
    # Space: O(m + n)
    def multiply(self, num1: str, num2: str) -> str:
        if num1 == "0" or num2 == "0":
            return "0"
        m, n = len(num1), len(num2)
        result = [0] * (m + n)
        for i in range(m - 1, -1, -1):
            for j in range(n - 1, -1, -1):
                product = (ord(num1[i]) - ord("0")) * (ord(num2[j]) - ord("0"))
                total = product + result[i + j + 1]
                result[i + j + 1] = total % 10
                result[i + j] += total // 10
        return "".join(str(x) for x in result).lstrip("0")