7. Reverse Integer

https://leetcode.com/problems/reverse-integer/

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.