CircularLinkedList.java

import java.util.Scanner;
public class CircularLinkedList {
    class Node{
        int data;
        Node next;
        Node(int data){
            this.data=data;
            this.next=null; }}
    Node head=null;
    Node tail=null;
    public CircularLinkedList(){
        this.head=null;
        this.tail=null;
    }
    public void insert(int data){
        Node newNode = new Node(data);
        if (head == null) {
            head = newNode;
            tail = newNode;
            tail.next = head;
            return;
        }
        tail.next = newNode;
        newNode.next = head;
        tail = newNode;
    }
    public void display(){
        if (head == null) {
            System.out.println("List is empty");
            return;
        }
        Node curr = head;
        System.out.println("Circular Linked List: ");
        do{
            System.out.print(curr.data+" -> ");
            curr = curr.next;
        } while(curr!=head);
        System.out.println("HEAD");
    }
    public void delete(int data){
        Node node = head;
        if (node == null) {
            System.out.println("List is empty");
            return;
        }
        if(head==tail && head.data==data){
            head=null;
            tail=null;
            System.out.println("Deleted: "+data);
            return;
        }
        if(node.data==data){
            head=head.next;
            tail.next=head;
            System.out.println("Deleted: "+data);
            return;
        }
        do {
            Node next = node.next;
            if (next.data == data) {
                node.next = next.next;
                if (next == tail) tail = node;
                System.out.println("Deleted: " +data);
                return;
            }
            node = node.next;
        } while (node != head);
        System.out.println("Value not found");
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        CircularLinkedList list = new CircularLinkedList();
        int choice, val;
        do {
            System.out.println("\n1. Insert");
            System.out.println("2. Delete");
            System.out.println("3. Display");
            System.out.println("4. Exit");
            System.out.print("Enter choice: ");
            choice = sc.nextInt();
            switch (choice) {
                case 1:
                    System.out.print("Enter value: ");
                    val = sc.nextInt();
                    list.insert(val);
                    break;
                case 2:
                    System.out.print("Enter value to delete: ");
                    val = sc.nextInt();
                    list.delete(val);
                    break;
                case 3:
                    list.display();
                    break;
                case 4:
                    System.out.println("Exiting...");
                    break;
                default:
                    System.out.println("Invalid choice");
            }
        } while (choice != 4); }}