reorganise directories

upd chapter_01/binary.py

chapter_03/README.md

@@ -0,0 +1,10 @@
+# Recursion
+
+Recursive functions must have both:
+
+-   one or more base cases
+-   a recursive case
+
+The base cases are required to ensure the recursion stops when meeting a condition
+
+The recursive case adds functions onto the call stack and completes each one top down.

chapter_03/recursion.py

@@ -0,0 +1,7 @@
+def factorial(x):
+    if x == 1:  # This is the base case
+        return 1
+    return x * factorial(x - 1)  # This is the recursive case
+
+
+print(factorial(4))