自己写的：
class Solution:def addStrings(self, num1: str, num2: str) -> str:# 将两个字符串转换为整数num1_int = self.strToInt(num1)num2_int = self.strToInt(num2)# 将两个整数相加，并将结果转换为字符串res = self.IntToStr(num1_int + num2_int)return res# 将字符串转换为整数def strToInt(self, num_str):num_li = []# 遍历字符串，将每个字符转换为整数并存储在列表中for i in num_str:num_li.append(int(i))n = len(num_li)res = 0# 将整数列表转换为整数for i in range(n):res += num_li[i] * 10 ** (n - i - 1)return res# 将整数转换为字符串def IntToStr(self, num_int):str_save = ''flag = True# 循环直到整数为0while flag:# 将整数的每一位取出并添加到字符串中str_save = str(num_int % 10) + str_savenum_int //= 10# 检查是否还有剩余的数字if num_int > 0:flag = Trueelse:flag = Falsereturn str_save
