Deletion in Circular Linked List

February 21, 2023

JAVA Program to Delete a Node of a Circular Linked List

A Circular Linked List is collection of data elements where each element points towards the next element and the last Element points towards the First Element Hence forming a Loop. Below on this page we will learn about Circular Linked List Deletion in java.

Algorithm for deletion from beginning of a circular linked list

deleteFirst()
IF head == null
- return
ELSE IF head != tail
- head = head -> next
- tail -> next = head
ELSE
- head = tail = null

public void deleteFirst() {  
        if(head == null) {  
            return;  
        }  
        else {  
            if(head != tail ) {  
                head = head.next;  
                tail.next = head;  
            }  
            else {  
                head = tail = null;  
            }  
        }  
    }

Algorithm for deletion from last of a circular linked list

deleteLast()
IF head == null
- return
ELSE IF head != tail
- Node current = head
- WHILE current->next != tail
  - current = current-> next
  - tail = current;
  - tail -> next = head
ELSE
- head = tail = null

public void deleteLast() {
        if(head == null) {
            return;
        }
        else {
            if(head != tail ) {
                Node current = head;
                while(current.next != tail) {
                    current = current.next;
                }
                tail = current;
                tail.next = head;
            }
            else {
                head = tail = null;
            }
        }
    }

Deletion from beginning in Circular Linked List

Sorted Insert In Circular Linked List

Insertion and Deletion in a Circular Linked List

Split a Circular Linked List in two halves

Count nodes in Circular Linked List

Algorithm for deletion from last of a circular linked list

deleteLast()
IF head == null
- return
ELSE
- WHILE (–n>0)
  - previous = temp;
  - temp = temp.next;
- previous.next = temp.next;

Code for deletion of a node in circular Linked List in Java

Method 1

Method 2

Method 1

Run

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Main Obj = new Main();
        Obj.add(10);
        Obj.add(20);
        Obj.add(30);
        Obj.add(40);
        Obj.add(50);
        Obj.add(60);

        System.out.println("List Before Deletion");
        Obj.print();

        System.out.println("List After Deleting first node");
        Obj.deleteFirst();
        Obj.print();

        System.out.println("List After Deleting last node");
        Obj.deleteLast();
        Obj.print();

        Obj.deleteNthNode(2);
        System.out.println("List After Deleting 2nd node");
        Obj.print();
    }
    public class Node{
        int element;
        Node next;

        public Node(int element) {
            this.element = element;
        }
    }
    public Node head = null;
    public Node tail = null;

    public void print() {
        Node temp = head;
        if(head == null) {
            System.out.println("null");
        }
        else {
            do{
                System.out.print(" "+ temp.element);
                temp = temp.next;
            }while(temp != head);
            System.out.println();
        }
    }

    public void add(int element){
        Node newNode = new Node(element);
        if(head == null) {
            head = newNode;
            tail = newNode;
            newNode.next = head;
        }
        else {
            tail.next = newNode;
            tail = newNode;
            tail.next = head;
        }
    }



    public void deleteFirst() {
        if(head == null) {
            return;
        }
        else {
            if(head != tail ) {
                head = head.next;
                tail.next = head;
            }
            else {
                head = tail = null;
            }
        }
    }


    public void deleteLast() {
        if(head == null) {
            return;
        }
        else {
            if(head != tail ) {
                Node current = head;
                while(current.next != tail) {
                    current = current.next;
                }
                tail = current;
                tail.next = head;
            }
            else {
                head = tail = null;
            }
        }
    }

    public int calcLen(){
        int len = 0;
        Node temp=head;

        while(temp!=tail){
            temp = temp.next;
            len++;
        }
        return len;
    }

    public void deleteNthNode(int n)
    {
        int len = calcLen();

        // Can only insert after 1st position
        // Can't insert if position to insert is greater than size of Linked List
        if(n < 1 || n > len)
        {
            System.out.println("Can't delete\n");

        }
        else
        {
            if(n == 1)
            {
                head = head.next;
                return;
            }
            // required to traverse
            Node temp = head;
            Node previous = null;

            // traverse to the nth node
            while(--n > 0) {
                previous = temp;
                temp = temp.next;
            }
            // assigned next node of the previous node to nth node's next
            previous.next = temp.next;
            System.out.println("Deleted: " + temp.element);
        }
    }
}

Output

List Before Deletion
 10 20 30 40 50 60
List After Deleting first node
 20 30 40 50 60
List After Deleting last node
 20 30 40 50
Deleted: 30
List After Deleting 2nd node
 20 40 50

Method 2

Run

import java.lang.*;
public class Main {
    public static void main(String[] args) {
        Main Obj = new Main();
        Obj.add(10);
        Obj.add(20);
        Obj.add(30);
        Obj.add(40);
        Obj.add(50);
        Obj.add(60);

        System.out.println("List Before Deletion");
        Obj.print();

        System.out.println("List After Deleting first node");
        Obj.deleteFirst();
        Obj.print();

        System.out.println("List After Deleting last node");
        Obj.deleteLast();
        Obj.print();

        Obj.deletenth(2);
        System.out.println("List After Deleting 2nd node");
        Obj.print();

    }
    public class Node{
        int element;
        Node next;
        Node prev;

        public Node(int element) {
            this.element = element;
        }
    }
    public Node head = null;
    public Node tail = null;
    public void print() {
        Node temp = head;
        if(head == null) {
            System.out.println("null");
        }
        else {
            do{
                System.out.print(" "+ temp.element);
                temp = temp.next;
            }while(temp != head);
            System.out.println();
        }
    }

    public void add(int element){
        Node newNode = new Node(element);
        if(head == null) {
            head = newNode;
            tail = newNode;
            newNode.next = head;
            newNode.prev=head;
        }
        else {
            tail.next = newNode;
            newNode.prev=tail;
            tail = newNode;
            tail.next = head;
        }
    }
    public int Length(Node head)
    {
        Node current = head;
        int count = 0;
        // if list is empty
        // simply return length zero
        if (head == null)
        {
            return 0;
        }
        // traverse forst to last node
        else
        {
            do
            {
                current = current.next;
                count++;
            } while (current != head);
        }
        return count;
    }

    public void deleteFirst() {
        if(head == null) {
            return;
        }
        else {
            if(head != tail ) {
                head = head.next;
                tail.next = head;
            }
            else {
                head = tail = null;
            }
        }
    }

    public void deleteLast() {
        if(head == null) {
            return;
        }
        else {
            if(head != tail ) {
                Node current = head;
                while(current.next != tail) {
                    current = current.next;
                }
                tail = current;
                tail.next = head;
                head.prev=tail;
            }
            else {
                head = tail = null;
            }
        }
    }


    public void deletenth (int n)
    {
        if (head == null)
        {
            return;
        }
        else
        {
            Node current = head;
            int pos = n;
            for (int i = 1; i < pos; i++)
            {
                current = current.next;
            }
            if (current == head)
            {
                head = current.next;
            }
            else if (current == null)
            {
                current = current.prev;
            }
            else
            {
                current.prev.next = current.next;
                current.next.prev = current.prev;
            }
            //Delete the middle node
            current = null;
        }
    }


    void printList ()
    {
        //Node current will point to head
        Node curr = head;
        if (head == null)
        {
            System.out.println ("List is empty");
            return;
        }
        while (curr != null)
        {
            //Prints each node by increasing order of the pointer
            System.out.print (curr.element + " ");
            curr = curr.next;
        }
        System.out.println ();
    }

}

Output

List Before Deletion
 10 20 30 40 50 60
List After Deleting first node
 20 30 40 50 60
List After Deleting last node
 20 30 40 50
List After Deleting 2nd node
 20 40 50

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Introduction to Circular Linked List
Circular Linked List Applications
Circular Linked List in – C | C++ | Java
Insertion in Circular Linked List – C | C++ | Java
- Insertion at the beginning– C | C++ | Java
- Insertion at the end – C | C++ | Java
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Deletion in Circular Linked List – C | C++ | Java
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- Deletion from end in Circular Linked List – C | C++ | Java
Insertion and Deletion in a Circular Linked List – C | C++ | Java
Split a Circular Linked List in two halves – C | C++ | Java
Count nodes in Circular Linked List – C | C++ | Java
Sorted Insert In Circular Linked List – C | C++ | Java
Insertion in the middle in Circular Linked List – C | C++ | Java