Python program to delete a new node from the end of the doubly linked list

When it is required to delete a node from the end of a doubly linked list, a ‘Node’ class needs to be created. In this class, there are three attributes, the data that is present in the node, the access to the next node of the linked list, and the access to the previous node of the linked list.

Below is a demonstration for the same −

Example

class Node:
   def __init__(self, my_data):
      self.prev = None
      self.data = my_data
      self.next = None
class double_list:
   def __init__(self):
      self.head = None
      self.tail = None
   def add_data(self, my_data):
      new_node = Node(my_data)
      if(self.head == None):
         self.head = self.tail = new_node;
         self.head.previous = None;
         self.tail.next = None;
      else:
         self.tail.next = new_node;
         new_node.previous = self.tail;
         self.tail = new_node;
         self.tail.next = None;
   def print_it(self):
      curr = self.head
      if (self.head == None):
         print("The list is empty")
         return
      print("The nodes in the doubly linked list are :")
      while curr != None:
         print(curr.data)
         curr = curr.next
   def delete_from_end(self):
      if(self.head == None):
         return;
      else:
         if(self.head != self.tail):
            self.tail = self.tail.previous
            self.tail.next = None;
         else:
            self.head = self.tail = None;
my_instance = double_list()
print("Elements are being added to the doubly linked list")
my_instance.add_data(10)
my_instance.add_data(24)
my_instance.add_data(54)
my_instance.add_data(77)
my_instance.add_data(92)
my_instance.print_it()
while(my_instance.head != None):
my_instance.delete_from_end();
print("The list after deleting the element from the end is : ");
my_instance.print_it();

Output

Elements are being added to the doubly linked list
The nodes in the doubly linked list are :
10
24
54
77
92
The list after deleting the element from the end is :
The nodes in the doubly linked list are :
10
24
54
77
The list after deleting the element from the end is :
The nodes in the doubly linked list are :
10
24
54
The list after deleting the element from the end is :
The nodes in the doubly linked list are :
10
24
The list after deleting the element from the end is :
The nodes in the doubly linked list are :
10
The list after deleting the element from the end is :
The list is empty

Explanation

• The ‘Node’ class is created.
• Another class with required attributes is created.
• A method named ‘add_data’ is defined, that is used to add data to the doubly linked list.
• Another method named ‘print_it’ is defined, that displays the nodes of the circular linked list.
• Another method named ‘delete_from_end’ is defined, that deletes the node from the end, i.e the ‘tail’ node and makes the previous node as the tail node in the circular linked list.
• An object of the ‘double_list’ class is created, and the methods are called on it to delete a node from the beginning of the doubly linked list.
• An ‘init’ method is defined, that the root, head, and tail nodes of the doubly linked list to None.
• The list is iterated over, and every node from the end of the linked list is deleted until its empty.
• This is displayed on the console using the ‘print_it’ method.