leetcode 258: Add Digits

Add Digits

Total Accepted: 5383
Total Submissions: 11876

Given a non-negative integer

num

, repeatedly add all its digits until the result has only one digit.

For example:

Given

num = 38

, 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?

[思路]

[CODE]

public class Solution {
public int addDigits(int num) {
return 1 + (num-1) % 9;
}
}