upload 1 answer, Aug 16th

Author: stevenlordiam

Easy/AddDigits.java

@@ -0,0 +1,35 @@
+/*
+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?
+
+Hint:
+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(https://en.wikipedia.org/wiki/Digital_root) useful
+*/
+
+public class AddDigits {
+    public int addDigits(int num) {
+        String str = String.valueOf(num);
+        while(str.length()>1){
+            num =0;
+            for(int i =0;i<str.length();i++){
+                num += str.charAt(i)-'0';
+            }
+            str = String.valueOf(num);
+        }
+        return num;
+    }
+}
+
+/*
+Reference:
+https://leetcode.com/discuss/52140/share-my-simple-to-understand-no-tricky-java-solution
+https://leetcode.com/discuss/52092/256ms-java-one-line-solution
+*/