Python program to create a doubly linked list of n nodes and count the number of nodes

When it is required to count the number of nodes in 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.

In a doubly linked list, the nodes have pointers. The current node would have a pointer to the next node as well as the previous node. The last value in the list will have ‘NULL’ value in the next pointer. It can be traversed in both the directions.

Below is a demonstration for the same −

Example

 Live Demo

class Node:
   def __init__(self, my_data):
      self.prev = None
      self.data = my_data
      self.next = None
class count_val:
   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 count_node(self):
      my_counter = 0;
      curr = self.head;
      while(curr != None):
         my_counter = my_counter + 1;
         curr = curr.next;
      return my_counter;
   def print_it(self):
      curr = self.head
      if (self.head == None):
         print("The list is empty")
         return
      print("The nodes are :")
      while curr != None:
         print(curr.data)
         curr = curr.next
my_instance = count_val()
print("Elements are being added to the list")
my_instance.add_data(10)
my_instance.add_data(14)
my_instance.add_data(24)
my_instance.add_data(17)
my_instance.add_data(22)
my_instance.print_it()
print("The nodes in the doubly linked list are : ")
print(my_instance.count_node())

Output

Elements are being added to the list
The nodes are :
10
14
24
17
22
The nodes in the doubly linked list are :
5

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 ‘count_node’ is defined, that helps in fetching the number of nodes in the doubly linked list.
• Another method named ‘print_it’ is defined, that displays the nodes of the circular linked list.
• An object of the ‘count_val’ class is created, and the methods are called on it to convert the doubly linked list to a ternary tree.
• An ‘init’ method is defined, that the root, head, and tail nodes of the doubly linked list to None.
• The ‘count_node’ method is called.
• It iterates through the doubly linked list, and gets the number of nodes in the list.
• This is displayed on the console using the ‘print_it’ method.

AmitDiwan

Published on 11-Mar-2021 11:46:17

• Related Questions & Answers
• Python program to create a Circular Linked List of N nodes and count the number of nodes
• Golang program to count the number of nodes in a doubly linked list.
• Python program to rotate doubly linked list by N nodes
• Python program to create a doubly linked list of n nodes and display it in reverse order
• Golang Program to count the number of nodes in a linked list.
• Delete N nodes after M nodes of a linked list in C++ program
• Program to delete n nodes after m nodes from a linked list in Python
• Delete N nodes after M nodes of a linked list in C++?
• Python program to create a Circular Linked List of n nodes and display it in reverse order
• Program to count number of BST with n nodes in Python
• Program to reverse inner nodes of a linked list in python
• Product of the nodes of a Singly Linked List
• Find count of common nodes in two Doubly Linked Lists in C++
• Product of the alternate nodes of linked list
• Python program to create and display a doubly linked list