Complete guide to mastering Circular Linked Lists in 2025 with this beginner-to-advanced tutorial! Learn how circular linked lists work, their types, operations, and real-life applications through clear explanations, code examples in C, C++, Java, Python, and JavaScript, and step-by-step implementations. This post also covers time and space complexity, interview FAQs, help you crack coding interviews and academic exams. Perfect for students, developers, and data structure enthusiasts!

What is a Circular Linked List?

A Circular Linked List is a variation of the linked list in which the last node points back to the first node instead of pointing to NULL. This creates a looped structure where you can traverse endlessly through the list starting from any node.

🔁 In a circular linked list, you can go from tail to head seamlessly — it’s like a roundabout with no end!

Why Learn Circular Linked Lists?

Learning about Circular Linked Lists is crucial for understanding how dynamic data structures work in memory. They are especially useful for:

• Circular buffers (ring buffers)
• Multiplayer game round-robin scheduling
• Task scheduling algorithms
• Data streaming

Types of Circular Linked List

1. Singly Circular Linked List
   Each node has a data and a next pointer, and the next of the last node points to the first node.
2. Doubly Circular Linked List
   Each node has data, next, and prev pointers. The next of the last node connects to the first node and the prev of the first node connects to the last.

Circular Linked List Operations

1. Insertion

• At the beginning
• At the end
• After a specific node

2. Deletion

• From the beginning
• From the end
• A specific node

3. Traversal

• Start from any node and keep moving until you’re back to the same node.

// Example: Circular Linked List Traversal in C
void traverse(struct Node* head) {
    struct Node* temp = head;
    if (head != NULL) {
        do {
            printf("%d ", temp->data);
            temp = temp->next;
        } while (temp != head);
    }
}

Circular Linked List implementation

C Implementation CLL

#include <stdio.h>
#include <stdlib.h>

struct Node {
    int data;
    struct Node* next;
};

void traverse(struct Node* head) {
    if (head == NULL) return;
    struct Node* temp = head;
    do {
        printf("%d ", temp->data);
        temp = temp->next;
    } while (temp != head);
}

struct Node* insertEnd(struct Node* head, int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    if (!head) {
        newNode->next = newNode;
        return newNode;
    }
    struct Node* temp = head;
    while (temp->next != head) temp = temp->next;
    temp->next = newNode;
    newNode->next = head;
    return head;
}

✅ C++ Implementation CLL

#include <iostream>
using namespace std;

class Node {
public:
    int data;
    Node* next;
    Node(int val) {
        data = val;
        next = nullptr;
    }
};

void traverse(Node* head) {
    if (!head) return;
    Node* temp = head;
    do {
        cout << temp->data << " ";
        temp = temp->next;
    } while (temp != head);
}

Node* insertEnd(Node* head, int val) {
    Node* newNode = new Node(val);
    if (!head) {
        newNode->next = newNode;
        return newNode;
    }
    Node* temp = head;
    while (temp->next != head) temp = temp->next;
    temp->next = newNode;
    newNode->next = head;
    return head;
}

✅ Java Implementation CLL

class Node {
    int data;
    Node next;
    Node(int data) {
        this.data = data;
        this.next = null;
    }
}

public class CircularLinkedList {
    Node head;

    void traverse() {
        if (head == null) return;
        Node temp = head;
        do {
            System.out.print(temp.data + " ");
            temp = temp.next;
        } while (temp != head);
    }

    void insertEnd(int data) {
        Node newNode = new Node(data);
        if (head == null) {
            newNode.next = newNode;
            head = newNode;
            return;
        }
        Node temp = head;
        while (temp.next != head) temp = temp.next;
        temp.next = newNode;
        newNode.next = head;
    }
}

✅ Python Implementation CLL

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

class CircularLinkedList:
    def __init__(self):
        self.head = None

    def traverse(self):
        if not self.head:
            return
        temp = self.head
        while True:
            print(temp.data, end=' ')
            temp = temp.next
            if temp == self.head:
                break

    def insert_end(self, data):
        new_node = Node(data)
        if not self.head:
            new_node.next = new_node
            self.head = new_node
            return
        temp = self.head
        while temp.next != self.head:
            temp = temp.next
        temp.next = new_node
        new_node.next = self.head

✅ JavaScript Implementation CLL

class Node {
    constructor(data) {
        this.data = data;
        this.next = null;
    }
}

class CircularLinkedList {
    constructor() {
        this.head = null;
    }

    traverse() {
        if (!this.head) return;
        let temp = this.head;
        do {
            console.log(temp.data);
            temp = temp.next;
        } while (temp !== this.head);
    }

    insertEnd(data) {
        const newNode = new Node(data);
        if (!this.head) {
            newNode.next = newNode;
            this.head = newNode;
            return;
        }
        let temp = this.head;
        while (temp.next !== this.head) {
            temp = temp.next;
        }
        temp.next = newNode;
        newNode.next = this.head;
    }
}

Time & Space Complexity of Circular Linked List

Operation	Time Complexity	Space Complexity
Insert at End	O(n)	O(1)
Traverse	O(n)	O(1)
Delete Node	O(n)	O(1)
Search	O(n)	O(1)

⚠️ Note: You can make insertion O(1) by maintaining a tail pointer.

Advantages of Circular Linked List

• No NULL value at the end
• Ideal for implementing circular queues
• Efficient for round-robin scheduling
• Can traverse from any node

Disadvantages of Circular Linked List

• Slightly more complex insertion/deletion logic
• Risk of infinite loops if not handled properly

Circular Linked List vs Singly Linked List

Feature	Singly Linked List	Circular Linked List
End Pointer	Points to NULL	Points to head node
Traversal	Ends at NULL	Loops back to start
Use Case	Linear data	Circular scheduling

Real-world Use Cases of Circular Linked List

• Music playlist apps (loop through songs)
• Task scheduling in OS
• Live data streams
• Circular queues

FAQ of Circular Linked List

Conclusion

A Circular Linked List offers flexibility, especially when your use case involves continuous looping or round-based tasks. While it can be a bit more complex than a regular linked list, it brings efficiency and circular logic into dynamic data structures.

If you’re preparing for coding interviews, learning circular linked lists will give you an edge!

You can also Visit other tutorials of Embedded Prep 

• Multithreading in C++
• Multithreading Interview Questions
• Multithreading in Operating System
• Multithreading in Java
• POSIX Threads pthread Beginner’s Guide in C/C++
• Speed Up Code using Multithreading
• Limitations of Multithreading
• Common Issues in Multithreading
• Multithreading Program with One Thread for Addition and One for Multiplication
• Advantage of Multithreading
• Disadvantages of Multithreading
• Applications of Multithreading: How Multithreading Makes Modern Software Faster and Smarter”