London | 26-SDC-Jul | AYK | Sprint 2 | Implement a linked list in Python

Sprint-2/implement_linked_list/linked_list.py

@@ -0,0 +1,79 @@
+#node class to hold value and pointer
+class Node:
+    def __init__(self,data):
+        self.data = data
+        self.next = None   # pointer to next node
+        self.prev = None   # pointer to previous node
+
+#LinkedList class to manage chain of nodes
+
+class LinkedList:
+    def __init__(self):
+        self.head = None  # pointer to head
+        self.tail = None  # pointer to tail
+
+#insert at the beginning 
+
+    def push_head(self,data):
+        new_node = Node(data)
+
+        if not self.head:     #if the node is empty it will have both head & tail
+            self.head = new_node
+            self.tail = new_node
+        else:
+            new_node.next = self.head    # pointer to next new node 
+            self.head.prev = new_node   # pointer back to old node by new node
+            self.head = new_node        # move head pointer to new_node
+
+        return new_node
+
+   #remove data from last node & show the value
+    def pop_tail(self):
+        if not self.tail:      #if list is empty nothing to pop
+            return None 
+        tail_node = self.tail
+        removed_data = tail_node.data  # save value to return later
+
+        if self.head == self.tail:
+            self.head = None
+            self.tail = None
+        else:
+            self.tail = self.tail.prev
+            self.tail.next = None
+
+        return removed_data
+
+    #remove specific node
+
+    def remove(self,node):
+
+        #do  list is empty 
+        if not self.head:
+            return
+
+        # if node is head move head to next node 
+        if node == self.head:
+            self.head = node.next
+
+        #if node is tail move tail to prev node 
+        if node == self.tail:
+            self.tail = node.prev
+
+        #unlink node from its neighbors 
+        # check is there a node before 
+        if node.prev:
+            node.prev.next = node.next
+        #check is there a node after
+        if node.next:
+            node.next.prev = node.prev
+
+        # clean up pointers on the removed node
+
+        node.prev = None
+        node.next = None
+
+
+
+
+
+