Title: Add Digits Source: leetcode.com
Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.
For example:
Given num = 38, 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?
- A naive implementation of the above process is trivial. Could you come up with other methods?
- What are all the possible results?
- How do they occur, periodically or randomly?
- You may find this Wikipedia article useful.
Java solution
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/* https://leetcode.com/problems/add-digits/ */ class AddDigits { public int addDigits(int num) { if(num<10) return num; else { return num%9==0?9:num%9; } } public static void main(String args[]) { AddDigits a = new AddDigits(); System.out.println(a.addDigits(13)); } } |