Practice Add Digits
Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.
Problem Statement
Given an integer num, repeatedly add all its digits until the result has only one digit, and return it. Example 1: Example 2: Constraints: Follow up: Could you do it without any loop/recursion in O(1) runtime?
Source: Add Digits on LeetCode. Use the original task for its coding environment and submissions.
Examples
# Example 1
Input
num = 38
Output
2
# Example 2
Input
num = 0
Output
0
Constraints
0 <= num <= 2^31 - 1
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