From 37cf2028e69bc6abdaa0b38bda7517c92fec542b Mon Sep 17 00:00:00 2001
From: Donne Martin <donne.martin@gmail.com>
Date: Sat, 18 Jun 2016 11:46:00 -0400
Subject: [PATCH] Polish delete mid node challenge and solution

Update edge cases and tests.
---
 .../delete_mid/delete_mid_challenge.ipynb     | 10 ++++----
 .../delete_mid/delete_mid_solution.ipynb      | 25 +++++++++++++------
 linked_lists/delete_mid/test_delete_mid.py    | 17 ++++++++++---
 3 files changed, 36 insertions(+), 16 deletions(-)

diff --git a/linked_lists/delete_mid/delete_mid_challenge.ipynb b/linked_lists/delete_mid/delete_mid_challenge.ipynb
index 19ea34c..6034abe 100644
--- a/linked_lists/delete_mid/delete_mid_challenge.ipynb
+++ b/linked_lists/delete_mid/delete_mid_challenge.ipynb
@@ -170,21 +170,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 2",
+   "display_name": "Python 3",
    "language": "python",
-   "name": "python2"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "pygments_lexer": "ipython3",
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,
diff --git a/linked_lists/delete_mid/delete_mid_solution.ipynb b/linked_lists/delete_mid/delete_mid_solution.ipynb
index 71c7427..38b5364 100644
--- a/linked_lists/delete_mid/delete_mid_solution.ipynb
+++ b/linked_lists/delete_mid/delete_mid_solution.ipynb
@@ -96,9 +96,10 @@
     "class MyLinkedList(LinkedList):\n",
     "\n",
     "    def delete_node(self, node):\n",
-    "        if self.head is None:\n",
+    "        if self.head is None or node is None:\n",
     "            return\n",
-    "        if node is None:\n",
+    "        if self.head == node:\n",
+    "            self.head = None\n",
     "            return\n",
     "        if node.next is None:\n",
     "            node.data = None\n",
@@ -147,16 +148,25 @@
     "        head = Node(2)\n",
     "        linked_list = MyLinkedList(head)\n",
     "        linked_list.delete_node(head)\n",
-    "        assert_equal(linked_list.get_all_data(), [None])\n",
+    "        assert_equal(linked_list.get_all_data(), [])\n",
     "\n",
     "        print('Test: Multiple nodes')\n",
     "        linked_list = MyLinkedList(None)\n",
-    "        node0 = linked_list.insert_to_front(1)\n",
+    "        node0 = linked_list.insert_to_front(2)\n",
     "        node1 = linked_list.insert_to_front(3)\n",
     "        node2 = linked_list.insert_to_front(4)\n",
     "        node3 = linked_list.insert_to_front(1)\n",
-    "        linked_list.delete_node(node2)\n",
-    "        assert_equal(linked_list.get_all_data(), [1, 3, 1])\n",
+    "        linked_list.delete_node(node1)\n",
+    "        assert_equal(linked_list.get_all_data(), [1, 4, 2])\n",
+    "\n",
+    "        print('Test: Multiple nodes, delete last element')\n",
+    "        linked_list = MyLinkedList(None)\n",
+    "        node0 = linked_list.insert_to_front(2)\n",
+    "        node1 = linked_list.insert_to_front(3)\n",
+    "        node2 = linked_list.insert_to_front(4)\n",
+    "        node3 = linked_list.insert_to_front(1)\n",
+    "        linked_list.delete_node(node0)\n",
+    "        assert_equal(linked_list.get_all_data(), [1, 4, 3, None])\n",
     "\n",
     "        print('Success: test_delete_node')\n",
     "\n",
@@ -184,6 +194,7 @@
       "Test: Empty list, null node to delete\n",
       "Test: One node\n",
       "Test: Multiple nodes\n",
+      "Test: Multiple nodes, delete last element\n",
       "Success: test_delete_node\n"
      ]
     }
@@ -209,7 +220,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.4.3"
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,
diff --git a/linked_lists/delete_mid/test_delete_mid.py b/linked_lists/delete_mid/test_delete_mid.py
index ad19a34..5131c36 100644
--- a/linked_lists/delete_mid/test_delete_mid.py
+++ b/linked_lists/delete_mid/test_delete_mid.py
@@ -13,16 +13,25 @@ class TestDeleteNode(object):
         head = Node(2)
         linked_list = MyLinkedList(head)
         linked_list.delete_node(head)
-        assert_equal(linked_list.get_all_data(), [None])
+        assert_equal(linked_list.get_all_data(), [])
 
         print('Test: Multiple nodes')
         linked_list = MyLinkedList(None)
-        node0 = linked_list.insert_to_front(1)
+        node0 = linked_list.insert_to_front(2)
         node1 = linked_list.insert_to_front(3)
         node2 = linked_list.insert_to_front(4)
         node3 = linked_list.insert_to_front(1)
-        linked_list.delete_node(node2)
-        assert_equal(linked_list.get_all_data(), [1, 3, 1])
+        linked_list.delete_node(node1)
+        assert_equal(linked_list.get_all_data(), [1, 4, 2])
+
+        print('Test: Multiple nodes, delete last element')
+        linked_list = MyLinkedList(None)
+        node0 = linked_list.insert_to_front(2)
+        node1 = linked_list.insert_to_front(3)
+        node2 = linked_list.insert_to_front(4)
+        node3 = linked_list.insert_to_front(1)
+        linked_list.delete_node(node0)
+        assert_equal(linked_list.get_all_data(), [1, 4, 3, None])
 
         print('Success: test_delete_node')