update Ch13-Recursion

Author: rambasnet

notebooks/Ch13-Recursion.ipynb

@@ -267,15 +267,15 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 8,
    "metadata": {},
    "outputs": [],
    "source": [
     "# Finding Fibonacci number in series\n",
-    "# count = 0\n",
+    "count = 0\n",
     "def fib(n):\n",
-    "    #global count\n",
-    "    #count += 1\n",
+    "    global count\n",
+    "    count += 1\n",
     "    if n <= 1:\n",
     "        return n\n",
     "    f = fib(n-1) + fib(n-2)\n",
@@ -284,14 +284,22 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 9,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "fib was called 7049155 times.\n"
+     ]
+    }
+   ],
    "source": [
     "fib(32)\n",
-    "#print(count)\n",
-    "#assert fib(8) == 21\n",
-    "#assert fib(10) == 55"
+    "print(f'fib was called {count} times.')\n",
+    "assert fib(8) == 21\n",
+    "assert fib(10) == 55"
    ]
   },
   {
@@ -301,14 +309,38 @@
     "<img src=\"./resources/recursion-fib.svg\" width=\"50%\">\n",
     "\n",
     "### visualize fib(4) using pythontutor.com\n",
-    "- https://goo.gl/YNizhH"
+    "- https://goo.gl/YNizhH\n",
+    "\n",
+    "### You can timeit\n",
+    "\n",
+    "- use timeit function to see how long fib(n) takes"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 10,
    "metadata": {},
    "outputs": [],
+   "source": [
+    "from timeit import timeit"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "1.1521884420071729"
+      ]
+     },
+     "execution_count": 11,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
    "source": [
     "timeit(\"fib(32)\", globals=globals(), number=1)"
    ]
@@ -325,7 +357,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 12,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -339,18 +371,37 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 13,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "2178309\n"
+     ]
+    }
+   ],
    "source": [
     "print(fib_tail(32, 0, 1))"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 14,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "1.3885000953450799e-05"
+      ]
+     },
+     "execution_count": 14,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
    "source": [
     "timeit(\"fib_tail(32, 0, 1)\", globals=globals(), number=1)"
    ]