Leetcode Add Digits (law problem)

Test instructions

Converts an integer num into the and of all its decimal bits, repeating the operation until NUM has a number of digits of 1, which returns NUM.

Ideas:

The rule is that as the number of natural numbers is incremented, the result is also 1~9 within the loop, then the result is (num-1)%9+1. Note the case that NUM is 0.

1 classSolution {2  Public:3     intAdddigits (intnum) {4         if(!num)return 0;5         Else    return(num-1)%9+1;6     }7};

AC Code

Leetcode Add Digits (law problem)