Leetcode解题-Reverse Integer

发表于   |   分类于   |  

描述

Reverse digits of an integer.

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

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.

分析

算法没难度，细节实现题，测试用例里假设整数只有32位，但是Python在64位机器上int是64位的，而且一旦超出会自动转换为long，而long是没有精度限制的，所以说Python里整数不会溢出，这里为了过测试，要强行加上判断。

代码

Python

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
class Solution(object):
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        sign = 1 if x >= 0 else -1
        x = abs(x)
        r = 0
        while x:
            x, mod = divmod(x, 10)
            r = r * 10 + mod
            # overflow check
            if r > 2147483647:
                return 0
        return sign * r

热评文章