Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has only one digit, return it
{
public:
int addDigits(int num) {
return 1 + (num - 1) % 9;
}
};1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,……原文：http://www.cnblogs.com/julie-yang/p/6307724.html