Python program to create and display a Circular Linked List

A circular linked list is a data structure where the last node points back to the first node, forming a circle. Unlike regular linked lists that end with None, circular linked lists have no end − the traversal can continue indefinitely.

To implement a circular linked list in Python, we need two classes: a Node class to represent individual elements, and a CircularLinkedList class to manage the list operations.

Node Class Structure

Each node contains data and a reference to the next node ?

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

Circular Linked List Implementation

Here's a complete implementation that creates and displays a circular linked list ?

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

class CircularLinkedList:
    def __init__(self):
        self.head = None
    
    def add_data(self, data):
        new_node = Node(data)
        
        if not self.head:
            # First node - points to itself
            self.head = new_node
            new_node.next = self.head
        else:
            # Find the last node
            current = self.head
            while current.next != self.head:
                current = current.next
            
            # Insert new node at the beginning
            new_node.next = self.head
            current.next = new_node
            self.head = new_node
    
    def display(self):
        if not self.head:
            print("List is empty")
            return
        
        current = self.head
        print("The circular linked list is:")
        
        # Traverse until we come back to head
        while True:
            print(current.data)
            current = current.next
            if current == self.head:
                break

# Create and populate the circular linked list
my_list = CircularLinkedList()
my_list.add_data(47)
my_list.add_data(89) 
my_list.add_data(34)
my_list.add_data(11)

my_list.display()

The circular linked list is:
11
34
89
47

How It Works

The key difference from a regular linked list is in the linking logic:

• First node: Points to itself (new_node.next = self.head)
• Subsequent nodes: Last node's next always points to head
• Display: Uses while True loop with break condition when we reach head again

Visualization

Key Features

• No NULL termination: Last node points to the first node
• Continuous traversal: Can loop through the list indefinitely
• Efficient insertion: New nodes added at the beginning for O(1) complexity

Conclusion

Circular linked lists are useful for applications requiring continuous cycling through data, like round-robin scheduling. The key implementation detail is ensuring the last node always points back to the head, creating the circular structure.