TheDeveloperBlog.com

Home | Contact Us

C-Sharp | Java | Python | Swift | GO | WPF | Ruby | Scala | F# | JavaScript | SQL | PHP | Angular | HTML

Program to Delete a New Node From the Beginning of the Doubly Linked List

Program to Delete a New Node From the Beginning of the Doubly Linked List on fibonacci, factorial, prime, armstrong, swap, reverse, search, sort, stack, queue, array, linkedlist, tree, graph etc.

<< Back to PROGRAM

Q. Program to delete a new node from the beginning of the doubly linked list.

Explanation

In this program, we will create a doubly linked list and delete a node from the beginning of the list. If the list is empty, print the message "List is empty". If the list is not empty, we will make the head to point to next node in the list then; we will delete the first node.

Program to delete a new node from the beginning of the doubly linked list

Consider the above example, new was the head of the list. Make head to point to next node in the list. Now, node 1 will become the new head of the list thus, deleting node new.

Algorithm

  1. Define a Node class which represents a node in the list. It will have three properties: data, previous which will point to the previous node and next which will point to the next node.
  2. Define another class for creating a doubly linked list, and it has two nodes: head and tail. Initially, head and tail will point to null.
  3. deleteFromStart() will delete a node from the beginning of the list:
    1. It first checks whether the head is null (empty list) then, it will return from the function as there is no node present in the list.
    2. If the list is not empty, it will check whether the list has only one node.
    3. If the list has only one node, it will set both head and tail to null.
    4. If the list has more than one node then, the head will point to next node in the list and delete the old head node.
  4. display() will show all the nodes present in the list.
    1. Define a new node 'current' that will point to the head.
    2. Print current.data till current points to null.
    3. Current will point to the next node in the list in each iteration.

Solution

Python

#Represent a node of doubly linked list
class Node:
    def __init__(self,data):
        self.data = data;
        self.previous = None;
        self.next = None;
        
class DeleteStart:
    #Represent the head and tail of the doubly linked list
    def __init__(self):
        self.head = None;
        self.tail = None;
        
    #addNode() will add a node to the list
    def addNode(self, data):
        #Create a new node
        newNode = Node(data);
        
        #If list is empty
        if(self.head == None):
            #Both head and tail will point to newNode
            self.head = self.tail = newNode;
            #head's previous will point to None
            self.head.previous = None;
            #tail's next will point to None, as it is the last node of the list
            self.tail.next = None;
        else:
            #newNode will be added after tail such that tail's next will point to newNode
            self.tail.next = newNode;
            #newNode's previous will point to tail
            newNode.previous = self.tail;
            #newNode will become new tail
            self.tail = newNode;
            #As it is last node, tail's next will point to None
            self.tail.next = None;
            
    #deleteFromStart() will delete a node from the beginning of the list
    def deleteFromStart(self):
        #Checks whether list is empty
        if(self.head == None):
            return;
        else:
            #Checks whether the list contains only one element
            if(self.head != self.tail):
                #head will point to next node in the list
                self.head = self.head.next;
                #Previous node to current head will be made None
                self.head.previous = None;
                
            #If the list contains only one element 
            #then, it will remove the node, and now both head and tail will point to None

            else:
                self.head = self.tail = None;
                
    #display() will print out the nodes of the list
    def display(self):
        #Node current will point to head
        current = self.head;
        if(self.head == None):
            print("List is empty");
            return;
        while(current != None):
            #Prints each node by incrementing pointer.
            print(current.data),
            current = current.next;
        print();
       
dList = DeleteStart();
#Add nodes to the list
dList.addNode(1);
dList.addNode(2);
dList.addNode(3);
dList.addNode(4);
dList.addNode(5);
 
#Printing original list
print("Original List: ");
dList.display();
while(dList.head != None):
    dList.deleteFromStart();
    #Printing updated list
    print("Updated List: ");
    dList.display();

Output:

Original List: 
1 2 3 4 5 
Updated List: 
2 3 4 5 
Updated List: 
3 4 5 
Updated List: 
4 5 
Updated List: 
5 
Updated List: 
List is empty

C

#include <stdio.h>
 
//Represent a node of the doubly linked list

struct node{
    int data;
    struct node *previous;
    struct node *next;
};    
 
//Represent the head and tail of the doubly linked list
struct node *head, *tail = NULL;
 
//addNode() will add a node to the list
void addNode(int data) {
    //Create a new node
    struct node *newNode = (struct node*)malloc(sizeof(struct node));
    newNode->data = data;
    
    //If list is empty
    if(head == NULL) {
        //Both head and tail will point to newNode
        head = tail = newNode;
        //head's previous will point to NULL
        head->previous = NULL;
        //tail's next will point to NULL, as it is the last node of the list
        tail->next = NULL;
    }
    else {
        //newNode will be added after tail such that tail's next will point to newNode
        tail->next = newNode;
        //newNode's previous will point to tail
        newNode->previous = tail;
        //newNode will become new tail
        tail = newNode;
        //As it is last node, tail's next will point to NULL
        tail->next = NULL;
    }
}
 
//deleteFromStart() will delete a node from the beginning of the list
void deleteFromStart() {
    //Checks whether list is empty
    if(head == NULL) {
        return;
    }
    else {
        //Checks whether the list contains only one element
        if(head != tail) {
            //head will point to next node in the list
            head = head->next;
            //Previous node to current head will be made NULL
            head->previous = NULL;
        }
        //If the list contains only one element 
        //then, it will remove node and now both head and tail will point to NULL
        else {
            head = tail = NULL;
        }
    }
}
 
//display() will print out the nodes of the list
void display() {
    //Node current will point to head
    struct node *current = head;
    if(head == NULL) {
        printf("List is empty\n");
        return;
    }
    while(current != NULL) {
        //Prints each node by incrementing pointer.
        printf("%d ",current->data);
        current = current->next;
    }
    printf("\n");
}
    
int main()
{
    //Add nodes to the list
    addNode(1);
    addNode(2);
    addNode(3);
    addNode(4);
    addNode(5);
    
    //Printing original list
    printf("Original List: \n");
    display();
    while(head != NULL) {
        deleteFromStart();
        //Printing updated list
        printf("Updated List: \n");
        display();
    }    
 
    return 0;
}

Output:

Original List: 
1 2 3 4 5 
Updated List: 
2 3 4 5 
Updated List: 
3 4 5 
Updated List: 
4 5 
Updated List: 
5 
Updated List: 
List is empty

JAVA

public class DeleteStart {
    
    //Represent a node of the doubly linked list

    class Node{
        int data;
        Node previous;
        Node next;
        
        public Node(int data) {
            this.data = data;
        }
    }
    
    //Represent the head and tail of the doubly linked list
    Node head, tail = null;
    
    //addNode() will add a node to the list
    public void addNode(int data) {
        //Create a new node
        Node newNode = new Node(data);
        
        //If list is empty
        if(head == null) {
            //Both head and tail will point to newNode
            head = tail = newNode;
            //head's previous will point to null
            head.previous = null;
            //tail's next will point to null, as it is the last node of the list
            tail.next = null;
        }
        else {
            //newNode will be added after tail such that tail's next will point to newNode
            tail.next = newNode;
            //newNode's previous will point to tail
            newNode.previous = tail;
            //newNode will become new tail
            tail = newNode;
            //As it is last node, tail's next will point to null
            tail.next = null;
        }
    }
    
    //deleteFromStart() will delete a node from the beginning of the list
    public void deleteFromStart() {
        //Checks whether list is empty
        if(head == null) {
            return;
        }
        else {
            //Checks whether the list contains only one element
            if(head != tail) {
                //head will point to next node in the list
                head = head.next;
                //Previous node to current head will be made null
                head.previous = null;
            }
            //If the list contains only one element 
            //then, it will remove node and now both head and tail will point to null
            else {
                head = tail = null;
            }
        }
    }
    
    //display() will print out the nodes of the list
    public void display() {
        //Node current will point to head
        Node current = head;
        if(head == null) {
            System.out.println("List is empty");
            return;
        }
        while(current != null) {
            //Prints each node by incrementing the pointer.

            System.out.print(current.data + " ");
            current = current.next;
        }
        System.out.println();
    }
    
    public static void main(String[] args) {
        
        DeleteStart dList = new DeleteStart();
        //Add nodes to the list
        dList.addNode(1);
        dList.addNode(2);
        dList.addNode(3);
        dList.addNode(4);
        dList.addNode(5);
        
        //Printing original list
        System.out.println("Original List: ");
        dList.display();
        while(dList.head != null) {
            dList.deleteFromStart();
            //Printing updated list
            System.out.println("Updated List: ");
            dList.display();
        }
    }
}

Output:

Original List: 
1 2 3 4 5 
Updated List: 
2 3 4 5 
Updated List: 
3 4 5 
Updated List: 
4 5 
Updated List: 
5 
Updated List: 
List is empty

C#

 using System; 
namespace DoublyLinkedList 
{                     
    public class Program
    {
        //Represent a node of the doubly linked list

        public class Node<T>{
            public T data;
            public Node<T> previous;
            public Node<T> next;
            
            public Node(T value) {
                data = value;
            }
        }
        
        public class DeleteStart<T>{
            //Represent the head and tail of the doubly linked list
            public Node<T> head = null;             
             public Node<T> tail = null;
            
            //addNode() will add a node to the list
            public void addNode(T data) {
                //Create a new node
                Node<T> newNode = new Node<T>(data);
 
                //If list is empty
                if(head == null) {
                    //Both head and tail will point to newNode
                    head = tail = newNode;
                    //head's previous will point to null
                    head.previous = null;
                    //tail's next will point to null, as it is the last node of the list
                    tail.next = null;
                }
                else {
                    //newNode will be added after tail such that tail's next will point to newNode
                    tail.next = newNode;
                    //newNode's previous will point to tail
                    newNode.previous = tail;
                    //newNode will become new tail
                    tail = newNode;
                    //As it is last node, tail's next will point to null
                    tail.next = null;
                }
            }
    
            //deleteFromStart() will delete a node from the beginning of the list
            public void deleteFromStart() {
                //Checks whether list is empty
                if(head == null) {
                    return;
                }
                else {
                    //Checks whether the list contains only one element
                    if(head != tail) {
                        //head will point to next node in the list
                        head = head.next;
                        //Previous node to current head will be made null
                        head.previous = null;
                    }
                    //If the list contains only one element 
                    //then, it will remove node and now both head and tail will point to null
                    else {
                        head = tail = null;
                    }
                }
            }
    
            //display() will print out the nodes of the list
            public void display() {
                //Node current will point to head
                Node<T> current = head;
                if(head == null) {
                    Console.WriteLine("List is empty");
                    return;
                }
                while(current != null) {
                    //Prints each node by incrementing the pointer.

                    Console.Write(current.data + " ");
                    current = current.next;
                }
                Console.WriteLine();
            }
        }
        
        public static void Main()
        {
            DeleteStart<int> dList = new DeleteStart<int>();
            //Add nodes to the list
            dList.addNode(1);
            dList.addNode(2);
            dList.addNode(3);
            dList.addNode(4);
            dList.addNode(5);
 
            //Printing original list
            Console.WriteLine("Original List: ");
            dList.display();
            while(dList.head != null) {
                dList.deleteFromStart();
                //Printing updated list
                Console.WriteLine("Updated List: ");
                dList.display();
            }
        }    
    }
}

Output:

Original List: 
1 2 3 4 5 
Updated List: 
2 3 4 5 
Updated List: 
3 4 5 
Updated List: 
4 5 
Updated List: 
5 
Updated List: 
List is empty

PHP

<!DOCTYPE html>
<html>
<body>
<?php
//Represent a node of doubly linked list
class Node{
    public $data;
    public $previous;
    public $next;
    
    function __construct($data){
        $this->data = $data;
    }
}
class DeleteStart{
    //Represent the head and tail of the doubly linked list
    public $head;
    public $tail;
    function __construct(){
        $this->head = NULL;
        $this->tail = NULL;
    }
    
    //addNode() will add a node to the list
    function addNode($data) {
        //Create a new node
        $newNode = new Node($data);
        
        //If list is empty
        if($this->head == NULL) {
            //Both head and tail will point to newNode
            $this->head = $this->tail = $newNode;
            //head's previous will point to NULL
            $this->head->previous = NULL;
            //tail's next will point to NULL, as it is the last node of the list
            $this->tail->next = NULL;
        }
        else {
            //newNode will be added after tail such that tail's next will point to newNode
            $this->tail->next = $newNode;
            //newNode's previous will point to tail
            $newNode->previous = $this->tail;
            //newNode will become new tail
            $this->tail = $newNode;
            //As it is last node, tail's next will point to NULL
            $this->tail->next = NULL;
        }
    }
    
    //deleteFromStart() will delete a node from the beginning of the list
    function deleteFromStart() {
        //Checks whether list is empty
        if($this->head == NULL) {
            return;
        }
        else {
            //Checks whether the list contains only one element
            if($this->head != $this->tail) {
                //head will point to next node in the list
                $this->head = $this->head->next;
                //Previous node to current head will be made NULL
                $this->head->previous = NULL;
            }
            //If the list contains only one element 
            //then, it will remove node and now both head and tail will point to NULL
            else {
                $this->head = $this->tail = NULL;
            }
        }
    }
    
    //display() will print out the nodes of the list
    function display() {
        //Node current will point to head
        $current = $this->head;
        if($this->head == NULL) {
            print("List is empty <br>");
            return;
        }
        while($current != NULL) {
            //Prints each node by incrementing pointer.
            print($current->data . " ");
            $current = $current->next;
        }
        print("<br>");
    }
}
    
$dList = new DeleteStart();
//Add nodes to the list
$dList->addNode(1);
$dList->addNode(2);
$dList->addNode(3);
$dList->addNode(4);
$dList->addNode(5);
 
//Printing original list
print("Original List: <br>");
$dList->display();
while($dList->head != NULL) {
    $dList->deleteFromStart();
    //Printing updated list
    print("Updated List: <br>");
    $dList->display();
}
?>
</body>
</html>

Output:

Original List: 
1 2 3 4 5 
Updated List: 
2 3 4 5 
Updated List: 
3 4 5 
Updated List: 
4 5 
Updated List: 
5 
Updated List: 
List is empty

Next Topic#




Related Links:

.Net

.NET Array Dictionary List String 2D Async DataTable Dates DateTime Enum File For Foreach Format IEnumerable If IndexOf Lambda LINQ Parse Path Process Property Regex Replace Sort Split Static StringBuilder Substring Switch Tuple

Java

Core Array ArrayList HashMap String 2D Cast Character Console Deque Duplicates File For Format HashSet If IndexOf Lambda Math ParseInt Process Random Regex Replace Sort Split StringBuilder Substring Switch Vector While

Related Links

Adjectives Ado Ai Android Angular Antonyms Apache Articles Asp Autocad Automata Aws Azure Basic Binary Bitcoin Blockchain C Cassandra Change Coa Computer Control Cpp Create Creating C-Sharp Cyber Daa Data Dbms Deletion Devops Difference Discrete Es6 Ethical Examples Features Firebase Flutter Fs Git Go Hbase History Hive Hiveql How Html Idioms Insertion Installing Ios Java Joomla Js Kafka Kali Laravel Logical Machine Matlab Matrix Mongodb Mysql One Opencv Oracle Ordering Os Pandas Php Pig Pl Postgresql Powershell Prepositions Program Python React Ruby Scala Selecting Selenium Sentence Seo Sharepoint Software Spellings Spotting Spring Sql Sqlite Sqoop Svn Swift Synonyms Talend Testng Types Uml Unity Vbnet Verbal Webdriver What Wpf