Reverse a Number

Given a non-negative integer n, return the number you get when you write its digits in reverse order.

Zeros at the end of n move to the front of the reversed number, where they don't count: 120 reversed is 21. If n is 0, the answer is 0.

Example 1:

Input: n = 123
Output: 321
Explanation: The digits 1, 2, 3 read backwards are 3, 2, 1.

Example 2:

Input: n = 120
Output: 21
Explanation: Backwards the digits are 0, 2, 1, and 021 is the number 21.

Example 3:

Input: n = 7
Output: 7
Explanation: A number with one digit stays the same.

Constraints:

• 0 <= n <= 109