Added Day-26 Solution

Author: Gangadharbhuvan

Day-26_Add_Digits.py

@@ -0,0 +1,31 @@
+'''
+	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?
+
+   Hide Hint #1  
+A naive implementation of the above process is trivial. Could you come up with other methods?
+   Hide Hint #2  
+What are all the possible results?
+   Hide Hint #3  
+How do they occur, periodically or randomly?
+   Hide Hint #4  
+You may find this Wikipedia article useful.
+
+'''
+
+class Solution(object):
+    def addDigits(self, num):
+        while num>9:
+            res = 0
+            for i in str(num):
+                res+=int(i)
+                num = res
+        return num