leetcode

Add Digits:

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?

class Solution {

public:

int addDigits(int num) {

int divideNum = 0;

if( num < 10)

{

return num;

}else

{

while( num )

{

divideNum += num % 10;

num = num / 10;

}

addDigits( divideNum );

}

}

};