LeetCode 7.Reverse Integer

题目描述：

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

Note:
The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.

思路：
本题主要陷阱就是判断的是输出超过int型，而不是输入。

AC代码：

class Solution(object):    def reverse(self, x):        """        :type x: int        :rtype: int        """        isA = True        num_list = []        # 若为负数先转化为正数        if x < 0:            isA = False            x = abs(x)        while x != 0:            num_list.append(x % 10)            # 整除            x //= 10        ret = 0        for i in range(len(num_list)):            ret = ret * 10 + num_list[i]        # 溢出返回0,注意判断的是输出        if ret > 2 ** 31 or ret < -2 ** 31:            return 0        elif isA is False:            ret = -ret        return ret