Create DoublyLinkedList.py

Data Structures/DoublyLinkedList.py

@@ -0,0 +1,66 @@
+class Node: 
+
+    def __init__(self, data): 
+        self.data = data 
+        self.next = None
+        self.prev = None
+
+
+class DoublyLinkedList: 
+
+    def __init__(self): 
+        self.head = None
+
+    def pushfirst(self,new_data):#to add a new node in the beginning of the list 
+        new_node = Node(new_data)
+        new_node.next = self.head
+
+        if self.head is not None: 
+                self.head.prev = new_node 
+
+        self.head = new_node    
+
+
+    def pushafter(self,prev_node,new_node):
+        if prev_node is None :
+            print "The given previous node cannot be None"
+            return     
+
+        prev_node.next = new_node
+        new_node.next = prev_node.next
+        new_node.prev = prev_node
+
+        if new_node.next is not None:
+            new_node.next.prev = new_node
+
+
+
+    def pushlast(self,new_data):
+        new_node = Node(new_data)
+
+        if self.head is None:
+            new_node.prev = None
+            self.head = new_node
+            return 
+
+        last = self.head
+        while(last.next is not None):
+            last = self.next
+
+        last.next = new_node
+        new_node.prev = last
+
+    llist = DoublyLinkedList() 
+
+llist.pushlast(6) 
+
+
+llist.pushfirst(7) 
+
+
+llist.pushfirst(1) 
+
+
+llist.pushlast(4) 
+
+llist.pushafter(llist.head.next, 8)