Updated Node and LinkedList to allow setting the next pointer on init, or when appending a node. This is useful for circular linked list problems.

linked-lists/linked-list.ipynb

@@ -9,8 +9,7 @@
     "* [Clarifying Questions](#Clarifying-Questions)\n",
     "* [Test Cases](#Test-Cases)\n",
     "* [Algorithm](#Algorithm)\n",
-    "* [Code](#Code)\n",
+    "* [Code](#Code)"
-    "* [Pythonic-Code](#Pythonic-Code)"
    ]
   },
   {
@@ -155,15 +154,15 @@
     "%%writefile linked_list.py\n",
     "\n",
     "class Node(object):\n",
-    "    def __init__(self, data):\n",
+    "    def __init__(self, data, next_node=None):\n",
-    "        self.next = None\n",
+    "        self.next = next_node\n",
     "        self.data = data\n",
     "        \n",
     "    def __str__(self):\n",
     "        return self.data\n",
     "\n",
     "class LinkedList(object):\n",
-    "    def __init__(self, head):\n",
+    "    def __init__(self, head=None):\n",
     "        self.head = head\n",
     "    \n",
     "    def insert_to_front(self, data):\n",
@@ -176,10 +175,10 @@
     "            node.next = self.head\n",
     "            self.head = node\n",
     "            \n",
-    "    def append(self, data):\n",
+    "    def append(self, data, next_node=None):\n",
     "        if data is None:\n",
     "            return\n",
-    "        node = Node(data)\n",
+    "        node = Node(data, next_node)\n",
     "        if self.head is None:\n",
     "            self.head = node\n",
     "        else:\n",

linked-lists/linked_list.py

@@ -1,23 +1,15 @@
 
 class Node(object):
-    def __init__(self, data):
+    def __init__(self, data, next_node=None):
-        self.next = None
+        self.next = next_node
         self.data = data
         
     def __str__(self):
         return self.data
 
 class LinkedList(object):
-    def __init__(self, head):
+    def __init__(self, head=None):
         self.head = head
-
-    def __len__(self):
-        curr = self.head
-        counter = 0
-        while curr is not None:
-            counter += 1
-            curr = curr.next
-        return counter
     
     def insert_to_front(self, data):
         if data is None:
@@ -29,10 +21,10 @@ class LinkedList(object):
             node.next = self.head
             self.head = node
             
-    def append(self, data):
+    def append(self, data, next_node=None):
         if data is None:
             return
-        node = Node(data)
+        node = Node(data, next_node)
         if self.head is None:
             self.head = node
         else: