LeetCode Blog for course "Algorithms" -- Problem 7

Problem 7. Reverse Integer

Reverse digits of an integer.
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? i.e. 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.
The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.

My solution in Python:

class Solution(object):    def reverse(self, x):        """        :type x: int        :rtype: int        """        if x == 0:            return 0        neg = 1        if x < 0:            neg, x = -1, -x        reverse = 0        while x > 0:            reverse = reverse * 10 + x % 10            x = x / 10        reverse = reverse * neg        if reverse < -(1 << 31) or reverse > (1 << 31) - 1:            return 0        return reverse

Review:



This problem belongs to the more simple questions. However, we do need to consider the special conditions, such as numbers that exceeds the limit of 32 bits when reversed. Therefore, after reversing all the digits, we check to see whether it exceeds -(1<<31) or (1>>31), and if it does, we set the reversed value to 0.