leetcode: 7.Reverse Integer

# Reverse digits of an integer.
#
# Example1: x =  123, return  321
# Example2: x = -123, return -321
#
# click to show spoilers.
#
# Have you thought about this?
#
# Here are some good questions to ask before coding. 
# Bonus points for you if you have already thought through this!
#
# If the integer's last digit is 0, what should the output be? ie, cases such as 10, 100.
#
# Did you notice that the reversed integer might overflow? 
# Assume the input is a 32-bit integer, then the reverse of 1000000003 overflows. 
# How should you handle such cases?
#
# For the purpose of this problem, 
# assume that your function returns 0 when the reversed integer overflows.
#
# Note:
# The input is assumed to be a 32-bit signed integer. 
# Your function should return 0 when the reversed integer overflows.

class Solution():
    def reverse(self, x):
        l = list(str(abs(x)))
        l.reverse()
        rst = int(''.join(l))
        if rst > 2**31:
            return 0
        else:
            return rst if x>=0 else -rst


if __name__ == "__main__":
    assert Solution().reverse(123) == 321
    assert Solution().reverse(-321) == -123
    assert Solution().reverse(-100) == -1
    assert Solution().reverse(0) == 0
    assert Solution().reverse(1000000003) == 0