整数反转

class Solution:
    def reverse(self, x: int) -> int:
        flag = (1 if x < 0 else 0)
        num = abs(x)
        if num < 10:
            return x
        numList = []
        while num >= 10:
            numList.append(str(num % 10))
            num //= 10
        else:
            numList.append(str(num))
        number = int(''.join(numList))
        if flag == 1:
            if number >= 2147483648:
                return 0
            else:
                return -number
        else:
            if number >= 2147483647:
                return 0
            else:
                return number