7. Reverse Integer

Given a 32-bit signed integer, reverse digits of an integer.

Example 1:

Input: 123
Output: 321

Example 2:

Input: -123
Output: -321

Example 3:

Input: 120
Output: 21

Note:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

class Solution:
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        flag = True
        if x < 0:
            flag = False
            x = -x
        temp = []
        while x!=0:
            temp.append(x%10)
            x = int(x/10)
        for i in range(len(temp)):
            x = x*10+temp[i]
        if flag == False:
            x = -x
        if x >= 2**31-1 or x <= -2**31:
            return 0
        return x

注意判断大小是否超出是判断转换之后的数字。

ps.才知道博客园也可以用markdown的