Enhances 'base case' logic (#227)

Original function does not work when input array is empty or contains a single value. In the revised code, base case has been augmented to support those. Works successfully for all these test cases: find_max([1, 12, 8, 5]), find_max([]), find_max([1])

03_recursion/python/06_find_max.py

@@ -1,5 +1,9 @@
 def find_max(arr):
-    if len(arr) == 2:
+    if len(arr) == 0:
+        return 0
+    elif len(arr) == 1:
+        return arr[0]
+    elif len(arr) == 2:
         return arr[0] if arr[0] > arr[1] else arr[1]
     sub_max = find_max(arr[1:])
-    return arr[0] if arr[0] > sub_max else sub_max
+    return arr[0] if arr[0] > sub_max else sub_max