7. Reverse Integer

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

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.

Example 1:

Input: 123
Output: 321

Example 2:

Input: -123
Output: -321

Example 3:

Input: 120
Output: 21

Code：

class Solution(object):
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        x = int(str(x)[::-1]) if x >= 0 else - int(str(-x)[::-1])
        """
         if x >= 0:
            x = int(str(x)[::-1])  
        else:
            x = - int(str(-x)[::-1])
        """
        
        return x if x < 2147483648 and x >= -2147483648 else 0
        """
                if x < 2147483648 and x >= -2147483648:
            x=x
        else:
            x=0
        return x 
        """
# 利用Python的字符串反转操作来实现对整数的反转，反转后的字符串要重新转换为整数。
# 负数倒序时要先转正数
# 同上面一样，要注意正负和溢出情况。

****