Easy

Quiz

#258 Add Digits

APPROACH

Given a non-negative integer num, keep replacing it with the sum of its digits until only a single digit remains. Return that single digit.

Example 1:

Input: num = 38

Output: 2

Explanation: The process is

38 --> 3 + 8 --> 11

11 --> 1 + 1 --> 2

Since 2 has only one digit, return it.

Example 2:

Input: num = 0

Output: 0

1 of 4

1:00

What is the optimal approach for this problem?