Given N, reverse the digits of N.

Example 1:
Input: 200
Output: 2
Explanation: By reversing the digts of
number, number will change into 2.
Example 2:
Input : 122
Output: 221
Explanation: By reversing the digits of
number, number will change into 221.

Your Task:
You don't need to read or print anything. Your task is to complete the function reverse_digit() which takes N as input parameter and returns the reversed number.

Expected Time Complexity: O(Log(N))
Expected Space Complexity: O(1)

Constraints:
1 <= N <= 10^{15}

见题面

见题面