Day 26 of July LeetCode Challenge
1 min readJul 26, 2020
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Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.
Example:
Input: 38
Output: 2
Explanation: The process is like: 3 + 8 = 11, 1 + 1 = 2.
Since 2 has only one digit, return it.Follow up:
Could you do it without any loop/recursion in O(1) runtime?
