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.
class Solution {
public:
int addDigits(int num) {
//例如123 = 1*(99+1) + 2*(9+1) +3,算法要做的就是把9的倍数那一项删除
//用-1 +1的方式规避某项为9的问题
return (num - 1) % 9 + 1;
}
};