1.描述
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?
2.分析
3.代碼
class Solution {
public:
int addDigits(int num) {
if (num / 10 == 0) return num;
int newnum = 0;
while (num / 10) {
newnum += num % 10;
num /= 10;
}
newnum += num;
return addDigits(newnum);
}
};