LeetCode #7 Reverse Integer

Easy

Problem

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: [−2^31, 2^31 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

Solution

It’s trivial to reverse the integer but it should be noticed about boundaries of overflow.

Complexity

It’s trivial that it takes O(d) time for parsing all digits of x where d denotes to number of digits in x. And it only use O(1) extra space.