Create factorial.py

Fixes #12142

Author: singhvibhanshu

recursion/factorial.py

@@ -0,0 +1,7 @@
+def factorial(n):
+    if n == 0 or n == 1:
+        return 1
+    else:
+        return n * factorial(n - 1)
+      
+print(factorial(5)) # Example