7. Reverse Integer

题目描述

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.

Qiang的思路

class Solution:
    def reverse(self, x: int) -> int:
        MIN = - 2 ** 31
        MAX = 2 ** 31 - 1
        flag = 1 if x >= 0 else -1
        x *= flag
        res = 0
        while x != 0:
            res = res * 10 + x % 10
            x = x // 10
        res *= flag
        return res if MIN <= res <= MAX else 0