Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.
Example
Input: 38
Output: 2
Explanation: The process is like: 3 + 8 = 11, 1 + 1 = 2.
Since 2 has only one digit, return it.
Follow up
Could you do it without any loop/recursion in O(1) runtime?
Code
1 | public int addDigits(int num) { |