def reverse(self, x: int) -> int:
    y, res = abs(x), 0
    # 则其数值范围为 [−2^31, 2^31 − 1]
    boundry = (1<<31) -1 if x>0 else 1<<31
    while y != 0:
        res = res*10 +y%10
        if res > boundry :
            return 0
        y //=10
    return res if x >0 else -res