Added add_reverse challenge.

linked_lists/add_reverse/add_reverse_solution.ipynb

@@ -44,7 +44,7 @@
    "source": [
     "## Test Cases\n",
     "\n",
-    "* Empty list(s)\n",
+    "* Empty list(s) -> None\n",
     "* Add values of different lengths\n",
     "    * Input 1: 6->5->None\n",
     "    * Input 2: 9->8->7\n",
@@ -99,7 +99,7 @@
    },
    "outputs": [],
    "source": [
-    "%run linked_list.py"
+    "%run ../linked_list/linked_list.py"
    ]
   },
   {
@@ -111,11 +111,16 @@
    "outputs": [],
    "source": [
     "class MyLinkedList(LinkedList):\n",
+    "    \n",
     "    def __add__(self, first_node, second_node, carry):\n",
     "        if type(carry) != int and carry < 0:\n",
     "            raise ValueError('Invalid int argument: carry')\n",
+    "        \n",
+    "        # Base case\n",
     "        if first_node is None and second_node is None and carry == 0:\n",
     "            return None\n",
+    "        \n",
+    "        # Recursive case\n",
     "        value = carry\n",
     "        value += first_node.data if first_node is not None else 0\n",
     "        value += second_node.data if second_node is not None else 0\n",
@@ -159,17 +164,17 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Test: Empty list(s)\n",
-      "Test: Add values of different lengths\n",
-      "Test: Add values of same lengths\n",
-      "Success: test_add\n"
+      "Overwriting test_add_reverse.py\n"
      ]
     }
    ],
    "source": [
+    "%%writefile test_add_reverse.py\n",
     "from nose.tools import assert_equal\n",
     "\n",
-    "class Test(object):\n",
+    "\n",
+    "class TestAddReverse(object):\n",
+    "    \n",
     "    def test_add(self):\n",
     "        print('Test: Empty list(s)')\n",
     "        assert_equal(MyLinkedList().add(None, None), None)\n",
@@ -205,9 +210,34 @@
     "        \n",
     "        print('Success: test_add')\n",
     "\n",
+    "def main():\n",
+    "    test = TestAddReverse()\n",
+    "    test.test_add()\n",
+    "\n",
     "if __name__ == '__main__':\n",
-    "    test = Test()\n",
-    "    test.test_add()"
+    "    main()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Test: Empty list(s)\n",
+      "Test: Add values of different lengths\n",
+      "Test: Add values of same lengths\n",
+      "Success: test_add\n"
+     ]
+    }
+   ],
+   "source": [
+    "%run -i test_add_reverse.py"
    ]
   }
  ],