Linked List Insertion Notes - Class 8

Class 8: Linked List Insertion Notes - Class 8

The document Linked List Insertion Notes - Class 8 is a part of Class 8 category.
All you need of Class 8 at this link: Class 8

Inserting a node

All programs discussed in this post consider the following representations of linked list.

C++

All programs discussed in this post consider the following representations of linked list. 

// A linked list node

class Node

{

    public:

    int data;

    Node *next;

};

// This code is contributed by rathbhupendra

C

// A linked list node

struct Node

{

  int data;

  struct Node *next;

};

Java

// Linked List Class

class LinkedList

{

    Node head;  // head of list

 

    /* Node Class */

    class Node

    {

        int data;

        Node next;

          

        // Constructor to create a new node

        Node(int d) {data = d; next = null; }

    }

}

Python3

# Node class

class Node:

 

    # Function to initialize the node object

    def __init__(self, data):

        self.data = data  # Assign data

        self.next = None  # Initialize next as null

 

# Linked List class

class LinkedList:

   

    # Function to initialize the Linked List object

    def __init__(self):

        self.head = None

C#

/* Linked list Node*/

public class Node

{

    public int data;

    public Node next;

    public Node(int d) {data = d; next = null; }

}

Javascript

<script>

// Linked List Class

    var head; // head of list

 

    /* Node Class */

    class Node {

 

        // Constructor to create a new node

        constructor(d) {

            this.data = d;

            this.next = null;

        }

    }

// This code is contributed by todaysgaurav

</script>

In this post, methods to insert a new node in linked list are discussed. A node can be added in three ways 

  • At the front of the linked list 
  • After a given node. 
  • At the end of the linked list.

Add a node at the front: (4 steps process) 

The new node is always added before the head of the given Linked List. And newly added node becomes the new head of the Linked List. For example, if the given Linked List is 10->15->20->25 and we add an item 5 at the front, then the Linked List becomes 5->10->15->20->25. Let us call the function that adds at the front of the list is push(). The push() must receive a pointer to the head pointer, because push must change the head pointer to point to the new node.

Linked List Insertion Notes - Class 8

Following are the 4 steps to add a node at the front.

C++

/* Given a reference (pointer to pointer)

to the head of a list and an int,

inserts a new node on the front of the list. */

void push(Node** head_ref, int new_data)

{

    /* 1. allocate node */

    Node* new_node = new Node();

 

    /* 2. put in the data */

    new_node->data = new_data;

 

    /* 3. Make next of new node as head */

    new_node->next = (*head_ref);

 

    /* 4. move the head to point to the new node */

    (*head_ref) = new_node;

}

 

// This code is contributed by rathbhupendra

C

/* Given a reference (pointer to pointer) to the head of a list

   and an int,  inserts a new node on the front of the list. */

void push(struct Node** head_ref, int new_data)

{

    /* 1. allocate node */

    struct Node* new_node = (struct Node*) malloc(sizeof(struct Node));

  

    /* 2. put in the data  */

    new_node->data  = new_data;

  

    /* 3. Make next of new node as head */

    new_node->next = (*head_ref);

  

    /* 4. move the head to point to the new node */

    (*head_ref)    = new_node;

}

Java

/* This function is in LinkedList class. Inserts a

   new Node at front of the list. This method is

   defined inside LinkedList class shown above */

public void push(int new_data)

{

    /* 1 & 2: Allocate the Node &

              Put in the data*/

    Node new_node = new Node(new_data);

 

    /* 3. Make next of new Node as head */

    new_node.next = head;

 

    /* 4. Move the head to point to new Node */

    head = new_node;

}

Python3

# This function is in LinkedList class

# Function to insert a new node at the beginning

def push(self, new_data):

 

    # 1 & 2: Allocate the Node &

    #        Put in the data

    new_node = Node(new_data)

         

    # 3. Make next of new Node as head

    new_node.next = self.head

         

    # 4. Move the head to point to new Node

    self.head = new_node

C#

/* Inserts a new Node at front of the list. */

public void push(int new_data)

{

    /* 1 & 2: Allocate the Node &

               Put in the data*/

    Node new_node = new Node(new_data);

 

    /* 3. Make next of new Node as head */

    new_node.next = head;

 

    /* 4. Move the head to point to new Node */

    head = new_node;

}

Javascript

<script>

 

/* This function is in LinkedList class. Inserts a

   new Node at front of the list. This method is

   defined inside LinkedList class shown above */

    

 function push(new_data)

{

    /* 1 & 2: Allocate the Node &

              Put in the data*/

    var new_node = new Node(new_data);

 

    /* 3. Make next of new Node as head */

    new_node.next = head;

 

    /* 4. Move the head to point to new Node */

    head = new_node;

}

 

// This code contributed by Rajput-Ji

 

</script>

Time complexity of push() is O(1) as it does a constant amount of work.

Add a node after a given node: (5 steps process) 

We are given a pointer to a node, and the new node is inserted after the given node.

Linked List Insertion Notes - Class 8

C++

// Given a node prev_node, insert a

// new node after the given

// prev_node

void insertAfter(Node* prev_node, int new_data)

{

 

    // 1. Check if the given prev_node is NULL

    if (prev_node == NULL) {

        cout << "The given previous node cannot be NULL";

        return;

    }

 

    // 2. Allocate new node

    Node* new_node = new Node();

 

    // 3. Put in the data

    new_node->data = new_data;

 

    // 4. Make next of new node as

    // next of prev_node

    new_node->next = prev_node->next;

 

    // 5. move the next of prev_node

    // as new_node

    prev_node->next = new_node;

}

 

// This code is contributed by anmolgautam818,

// arkajyotibasak

C

/* Given a node prev_node, insert a new node after the given

prev_node */

void insertAfter(struct Node* prev_node, int new_data)

{

    /*1. check if the given prev_node is NULL */

    if (prev_node == NULL) {

        printf("the given previous node cannot be NULL");

        return;

    }

 

    /* 2. allocate new node */

    struct Node* new_node

        = (struct Node*)malloc(sizeof(struct Node));

 

    /* 3. put in the data */

    new_node->data = new_data;

 

    /* 4. Make next of new node as next of prev_node */

    new_node->next = prev_node->next;

 

    /* 5. move the next of prev_node as new_node */

    prev_node->next = new_node;

}

Java

/* This function is in LinkedList class.

Inserts a new node after the given prev_node. This method is

defined inside LinkedList class shown above */

public void insertAfter(Node prev_node, int new_data)

{

    /* 1. Check if the given Node is null */

    if (prev_node == null) {

        System.out.println(

            "The given previous node cannot be null");

        return;

    }

 

    /* 2. Allocate the Node &

    3. Put in the data*/

    Node new_node = new Node(new_data);

 

    /* 4. Make next of new Node as next of prev_node */

    new_node.next = prev_node.next;

 

    /* 5. make next of prev_node as new_node */

    prev_node.next = new_node;

}

Python3

# This function is in LinkedList class.

# Inserts a new node after the given prev_node. This method is

# defined inside LinkedList class shown above */

 

 

def insertAfter(self, prev_node, new_data):

 

    # 1. check if the given prev_node exists

    if prev_node is None:

        print("The given previous node must inLinkedList.")

        return

 

    # 2. Create new node &

    # 3. Put in the data

    new_node = Node(new_data)

 

    # 4. Make next of new Node as next of prev_node

    new_node.next = prev_node.next

 

    # 5. make next of prev_node as new_node

    prev_node.next = new_node

C#

/* Inserts a new node after the given prev_node. */

public void insertAfter(Node prev_node, int new_data)

{

    /* 1. Check if the given Node is null */

    if (prev_node == null) {

        Console.WriteLine("The given previous node"

                          + " cannot be null");

        return;

    }

 

    /* 2 & 3: Allocate the Node &

            Put in the data*/

    Node new_node = new Node(new_data);

 

    /* 4. Make next of new Node as

                next of prev_node */

    new_node.next = prev_node.next;

 

    /* 5. make next of prev_node

                    as new_node */

    prev_node.next = new_node;

}

Javascript

<script>

 

/* This function is in LinkedList class.

Inserts a new node after the given prev_node. This method is

defined inside LinkedList class shown above */

function insertAfter(prev_node , new_data)

{

 

    /* 1. Check if the given Node is null */

    if (prev_node == null)

    {

        document.write("The given previous node cannot be null");

        return;

    }

 

    /* 2. Allocate the Node &

    3. Put in the data*/

    var new_node = new Node(new_data);

 

    /* 4. Make next of new Node as next of prev_node */

    new_node.next = prev_node.next;

 

    /* 5. make next of prev_node as new_node */

    prev_node.next = new_node;

}

 

// This code is contributed by aashish1995

 

</script>

Time complexity of insertAfter() is O(1) as it does a constant amount of work.
Add a node at the end: (6 steps process) 

The new node is always added after the last node of the given Linked List. For example if the given Linked List is 5->10->15->20->25 and we add an item 30 at the end, then the Linked List becomes 5->10->15->20->25->30.
Since a Linked List is typically represented by the head of it, we have to traverse the list till the end and then change the next to last node to a new node.

Linked List Insertion Notes - Class 8

Following are the 6 steps to add node at the end.

C++

// Given a reference (pointer to pointer) to the head 

// of a list and an int, appends a new node at the end

void append(Node** head_ref, int new_data) 

   

    // 1. allocate node

    Node* new_node = new Node();

   

    // Used in step 5

    Node *last = *head_ref;

   

    // 2. Put in the data

    new_node->data = new_data; 

   

    // 3. This new node is going to be 

    // the last node, so make next of 

    // it as NULL

    new_node->next = NULL; 

   

    // 4. If the Linked List is empty,

    // then make the new node as head

    if (*head_ref == NULL) 

    { 

        *head_ref = new_node; 

        return; 

    } 

   

    // 5. Else traverse till the last node

    while (last->next != NULL)

    {

        last = last->next; 

    }

   

    // 6. Change the next of last node

    last->next = new_node; 

    return; 

 

// This code is contributed by anmolgautam818, arkajyotibasak

C

/* Given a reference (pointer to pointer) to the head

   of a list and an int, appends a new node at the end  */

void append(struct Node** head_ref, int new_data)

{

    /* 1. allocate node */

    struct Node* new_node = (struct Node*) malloc(sizeof(struct Node));

 

    struct Node *last = *head_ref;  /* used in step 5*/

  

    /* 2. put in the data  */

    new_node->data  = new_data;

 

    /* 3. This new node is going to be the last node, so make next

          of it as NULL*/

    new_node->next = NULL;

 

    /* 4. If the Linked List is empty, then make the new node as head */

    if (*head_ref == NULL)

    {

       *head_ref = new_node;

       return;

    } 

      

    /* 5. Else traverse till the last node */

    while (last->next != NULL)

        last = last->next;

  

    /* 6. Change the next of last node */

    last->next = new_node;

    return;   

}

Java

/* Appends a new node at the end.  This method is

   defined inside LinkedList class shown above */

public void append(int new_data)

{

    /* 1. Allocate the Node &

       2. Put in the data

       3. Set next as null */

    Node new_node = new Node(new_data);

 

    /* 4. If the Linked List is empty, then make the

           new node as head */

    if (head == null)

    {

        head = new Node(new_data);

        return;

    }

 

    /* 4. This new node is going to be the last node, so

         make next of it as null */

    new_node.next = null;

 

    /* 5. Else traverse till the last node */

    Node last = head;

    while (last.next != null)

        last = last.next;

 

    /* 6. Change the next of last node */

    last.next = new_node;

    return;

}

Python3

# This function is defined in Linked List class

# Appends a new node at the end.  This method is

# defined inside LinkedList class shown above

 

 

def append(self, new_data):

 

        # 1. Create a new node

        # 2. Put in the data

        # 3. Set next as None

        new_node = Node(new_data)

 

        # 4. If the Linked List is empty, then make the

        #    new node as head

        if self.head is None:

            self.head = new_node

            return

 

        # 5. Else traverse till the last node

        last = self.head

        while (last.next):

            last = last.next

 

        # 6. Change the next of last node

        last.next = new_node

C#

/* Appends a new node at the end. This method is

defined inside LinkedList class shown above */

public void append(int new_data)

{

    /* 1. Allocate the Node &

    2. Put in the data

    3. Set next as null */

    Node new_node = new Node(new_data);


    /* 4. If the Linked List is empty,

    then make the new node as head */

    if (head == null)

    {

        head = new Node(new_data);

        return;

    }


    /* 4. This new node is going to be

    the last node, so make next of it as null */

    new_node.next = null;


    /* 5. Else traverse till the last node */

    Node last = head;

    while (last.next != null)

        last = last.next;


    /* 6. Change the next of last node */

    last.next = new_node;

    return;

}

Javascript

<script>

 

/* Appends a new node at the end.  This method is

   defined inside LinkedList class shown above */

 function append(new_data)

{

    /* 1. Allocate the Node &

       2. Put in the data

       3. Set next as null */

    var new_node = new Node(new_data);

 

    /* 4. If the Linked List is empty, then make the

           new node as head */

    if (head == null)

    {

        head = new Node(new_data);

        return;

    }

 

    /* 4. This new node is going to be the last node, so

         make next of it as null */

    new_node.next = null;

 

    /* 5. Else traverse till the last node */

    var last = head;

    while (last.next != null)

        last = last.next;

 

    /* 6. Change the next of last node */

    last.next = new_node;

    return;

}

 

// This code contributed by aashish1995

</script>

Time complexity of append is O(n) where n is the number of nodes in the linked list. Since there is a loop from head to end, the function does O(n) work.
This method can also be optimized to work in O(1) by keeping an extra pointer to the tail of the linked list/
Following is a complete program that uses all of the above methods to create a linked list.

C++

// A complete working C++ program to demonstrate

//  all insertion methods on Linked List

#include <bits/stdc++.h>

using namespace std;

 

// A linked list node

class Node

{

    public:

    int data;

    Node *next;

};

 

/* Given a reference (pointer to pointer)

to the head of a list and an int, inserts

a new node on the front of the list. */

void push(Node** head_ref, int new_data)

{

    /* 1. allocate node */

    Node* new_node = new Node();

 

    /* 2. put in the data */

    new_node->data = new_data;

 

    /* 3. Make next of new node as head */

    new_node->next = (*head_ref);

 

    /* 4. move the head to point to the new node */

    (*head_ref) = new_node;

}

 

/* Given a node prev_node, insert a new node after the given

prev_node */

void insertAfter(Node* prev_node, int new_data)

{

    /*1. check if the given prev_node is NULL */

    if (prev_node == NULL)

    {

        cout<<"The given previous node cannot be NULL";

        return;

    }

 

    /* 2. allocate new node */

    Node* new_node = new Node();

 

    /* 3. put in the data */

    new_node->data = new_data;

 

    /* 4. Make next of new node as next of prev_node */

    new_node->next = prev_node->next;

 

    /* 5. move the next of prev_node as new_node */

    prev_node->next = new_node;

}

 

/* Given a reference (pointer to pointer) to the head

of a list and an int, appends a new node at the end */

void append(Node** head_ref, int new_data)

{

    /* 1. allocate node */

    Node* new_node = new Node();

 

    Node *last = *head_ref; /* used in step 5*/

 

    /* 2. put in the data */

    new_node->data = new_data;

 

    /* 3. This new node is going to be

    the last node, so make next of

    it as NULL*/

    new_node->next = NULL;

 

    /* 4. If the Linked List is empty,

    then make the new node as head */

    if (*head_ref == NULL)

    {

        *head_ref = new_node;

        return;

    }

 

    /* 5. Else traverse till the last node */

    while (last->next != NULL)

    {

        last = last->next;

    }

 

    /* 6. Change the next of last node */

    last->next = new_node;

    return;

}

 

// This function prints contents of

// linked list starting from head

void printList(Node *node)

{

    while (node != NULL)

    {

        cout<<" "<<node->data;

        node = node->next;

    }

}

 

/* Driver code*/

int main()

{

    /* Start with the empty list */

    Node* head = NULL;

     

    // Insert 6. So linked list becomes 6->NULL

    append(&head, 6);

     

    // Insert 7 at the beginning.

    // So linked list becomes 7->6->NULL

    push(&head, 7);

     

    // Insert 1 at the beginning.

    // So linked list becomes 1->7->6->NULL

    push(&head, 1);

     

    // Insert 4 at the end. So

    // linked list becomes 1->7->6->4->NULL

    append(&head, 4);

     

    // Insert 8, after 7. So linked

    // list becomes 1->7->8->6->4->NULL

    insertAfter(head->next, 8);

     

    cout<<"Created Linked list is: ";

    printList(head);

     

    return 0;

}

 

 

// This code is contributed by rathbhupendra, arkajyotibasak

C

// A complete working C program to demonstrate all insertion methods

// on Linked List

#include <stdio.h>

#include <stdlib.h>

 

// A linked list node

struct Node

{

  int data;

  struct Node *next;

};

 

/* Given a reference (pointer to pointer) to the head of a list and

   an int, inserts a new node on the front of the list. */

void push(struct Node** head_ref, int new_data)

{

    /* 1. allocate node */

    struct Node* new_node = (struct Node*) malloc(sizeof(struct Node));

 

    /* 2. put in the data  */

    new_node->data  = new_data;

 

    /* 3. Make next of new node as head */

    new_node->next = (*head_ref);

 

    /* 4. move the head to point to the new node */

    (*head_ref)    = new_node;

}

 

/* Given a node prev_node, insert a new node after the given

   prev_node */

void insertAfter(struct Node* prev_node, int new_data)

{

    /*1. check if the given prev_node is NULL */

    if (prev_node == NULL)

    {

      printf("the given previous node cannot be NULL");

      return;

    }

 

    /* 2. allocate new node */

    struct Node* new_node =(struct Node*) malloc(sizeof(struct Node));

 

    /* 3. put in the data  */

    new_node->data  = new_data;

 

    /* 4. Make next of new node as next of prev_node */

    new_node->next = prev_node->next;

 

    /* 5. move the next of prev_node as new_node */

    prev_node->next = new_node;

}

 

/* Given a reference (pointer to pointer) to the head

   of a list and an int, appends a new node at the end  */

void append(struct Node** head_ref, int new_data)

{

    /* 1. allocate node */

    struct Node* new_node = (struct Node*) malloc(sizeof(struct Node));

 

    struct Node *last = *head_ref;  /* used in step 5*/

 

    /* 2. put in the data  */

    new_node->data  = new_data;

 

    /* 3. This new node is going to be the last node, so make next of

          it as NULL*/

    new_node->next = NULL;

 

    /* 4. If the Linked List is empty, then make the new node as head */

    if (*head_ref == NULL)

    {

       *head_ref = new_node;

       return;

    }

 

    /* 5. Else traverse till the last node */

    while (last->next != NULL)

        last = last->next;

 

    /* 6. Change the next of last node */

    last->next = new_node;

    return;

}

 

// This function prints contents of linked list starting from head

void printList(struct Node *node)

{

  while (node != NULL)

  {

     printf(" %d ", node->data);

     node = node->next;

  }

}

 

/* Driver program to test above functions*/

int main()

{

  /* Start with the empty list */

  struct Node* head = NULL;

 

  // Insert 6.  So linked list becomes 6->NULL

  append(&head, 6);

 

  // Insert 7 at the beginning. So linked list becomes 7->6->NULL

  push(&head, 7);

 

  // Insert 1 at the beginning. So linked list becomes 1->7->6->NULL

  push(&head, 1);

 

  // Insert 4 at the end. So linked list becomes 1->7->6->4->NULL

  append(&head, 4);

 

  // Insert 8, after 7. So linked list becomes 1->7->8->6->4->NULL

  insertAfter(head->next, 8);

 

  printf("\n Created Linked list is: ");

  printList(head);

 

  return 0;

}

Java

// A complete working Java program to demonstrate all insertion methods

// on linked list

class LinkedList

{

    Node head;  // head of list

 

    /* Linked list Node*/

    class Node

    {

        int data;

        Node next;

        Node(int d) {data = d; next = null; }

    }

 

    /* Inserts a new Node at front of the list. */

    public void push(int new_data)

    {

        /* 1 & 2: Allocate the Node &

                  Put in the data*/

        Node new_node = new Node(new_data);

 

        /* 3. Make next of new Node as head */

        new_node.next = head;

 

        /* 4. Move the head to point to new Node */

        head = new_node;

    }

 

    /* Inserts a new node after the given prev_node. */

    public void insertAfter(Node prev_node, int new_data)

    {

        /* 1. Check if the given Node is null */

        if (prev_node == null)

        {

            System.out.println("The given previous node cannot be null");

            return;

        }

 

        /* 2 & 3: Allocate the Node &

                  Put in the data*/

        Node new_node = new Node(new_data);

 

        /* 4. Make next of new Node as next of prev_node */

        new_node.next = prev_node.next;

 

        /* 5. make next of prev_node as new_node */

        prev_node.next = new_node;

    }

    

    /* Appends a new node at the end.  This method is

       defined inside LinkedList class shown above */

    public void append(int new_data)

    {

        /* 1. Allocate the Node &

           2. Put in the data

           3. Set next as null */

        Node new_node = new Node(new_data);

 

        /* 4. If the Linked List is empty, then make the

              new node as head */

        if (head == null)

        {

            head = new Node(new_data);

            return;

        }

 

        /* 4. This new node is going to be the last node, so

              make next of it as null */

        new_node.next = null;

 

        /* 5. Else traverse till the last node */

        Node last = head;

        while (last.next != null)

            last = last.next;

 

        /* 6. Change the next of last node */

        last.next = new_node;

        return;

    }

 

    /* This function prints contents of linked list starting from

        the given node */

    public void printList()

    {

        Node tnode = head;

        while (tnode != null)

        {

            System.out.print(tnode.data+" ");

            tnode = tnode.next;

        }

    }

 

    /* Driver program to test above functions. Ideally this function

       should be in a separate user class.  It is kept here to keep

       code compact */

    public static void main(String[] args)

    {

        /* Start with the empty list */

        LinkedList llist = new LinkedList();

 

        // Insert 6.  So linked list becomes 6->NUllist

        llist.append(6);

 

        // Insert 7 at the beginning. So linked list becomes

        // 7->6->NUllist

        llist.push(7);

 

        // Insert 1 at the beginning. So linked list becomes

        // 1->7->6->NUllist

        llist.push(1);

 

        // Insert 4 at the end. So linked list becomes

        // 1->7->6->4->NUllist

        llist.append(4);

 

        // Insert 8, after 7. So linked list becomes

        // 1->7->8->6->4->NUllist

        llist.insertAfter(llist.head.next, 8);

 

        System.out.println("\nCreated Linked list is: ");

        llist.printList();

    }

}

// This code is contributed by Rajat Mishra

Python3

# A complete working Python program to demonstrate all

# insertion methods of linked list

 

# Node class

class Node:

 

    # Function to initialise the node object

    def __init__(self, data):

        self.data = data  # Assign data

        self.next = None  # Initialize next as null

 

 

# Linked List class contains a Node object

class LinkedList:

 

    # Function to initialize head

    def __init__(self):

        self.head = None

 

 

    # Function to insert a new node at the beginning

    def push(self, new_data):

 

        # 1 & 2: Allocate the Node &

        #        Put in the data

        new_node = Node(new_data)

 

        # 3. Make next of new Node as head

        new_node.next = self.head

 

        # 4. Move the head to point to new Node

        self.head = new_node

 

 

    # This function is in LinkedList class. Inserts a

    # new node after the given prev_node. This method is

    # defined inside LinkedList class shown above */

    def insertAfter(self, prev_node, new_data):

 

        # 1. check if the given prev_node exists

        if prev_node is None:

            print("The given previous node must inLinkedList.")

            return

 

        #  2. create new node &

        #      Put in the data

        new_node = Node(new_data)

 

        # 4. Make next of new Node as next of prev_node

        new_node.next = prev_node.next

 

        # 5. make next of prev_node as new_node

        prev_node.next = new_node

 

 

    # This function is defined in Linked List class

    # Appends a new node at the end.  This method is

    # defined inside LinkedList class shown above */

    def append(self, new_data):

 

        # 1. Create a new node

        # 2. Put in the data

        # 3. Set next as None

        new_node = Node(new_data)

 

        # 4. If the Linked List is empty, then make the

        #    new node as head

        if self.head is None:

            self.head = new_node

            return

 

        # 5. Else traverse till the last node

        last = self.head

        while (last.next):

            last = last.next

 

        # 6. Change the next of last node

        last.next =  new_node

 

 

    # Utility function to print the linked list

    def printList(self):

        temp = self.head

        while (temp):

            print(temp.data,end=" ")

            temp = temp.next

 

 

 

# Code execution starts here

if __name__=='__main__':

 

    # Start with the empty list

    llist = LinkedList()

 

    # Insert 6.  So linked list becomes 6->None

    llist.append(6)

 

    # Insert 7 at the beginning. So linked list becomes 7->6->None

    llist.push(7);

 

    # Insert 1 at the beginning. So linked list becomes 1->7->6->None

    llist.push(1);

 

    # Insert 4 at the end. So linked list becomes 1->7->6->4->None

    llist.append(4)

 

    # Insert 8, after 7. So linked list becomes 1 -> 7-> 8-> 6-> 4-> None

    llist.insertAfter(llist.head.next, 8)

 

    print('Created linked list is: ')

    llist.printList()

 

# This code is contributed by Manikantan Narasimhan

C#

// A complete working C# program to demonstrate

// all insertion methods on linked list

using System;

     

class GFG

{

    public Node head; // head of list

 

    /* Linked list Node*/

    public class Node

    {

        public int data;

        public Node next;

        public Node(int d) {data = d; next = null;}

    }

 

    /* Inserts a new Node at front of the list. */

    public void push(int new_data)

    {

        /* 1 & 2: Allocate the Node &

                Put in the data*/

        Node new_node = new Node(new_data);

 

        /* 3. Make next of new Node as head */

        new_node.next = head;

 

        /* 4. Move the head to point to new Node */

        head = new_node;

    }

 

    /* Inserts a new node after the given prev_node. */

    public void insertAfter(Node prev_node, int new_data)

    {

        /* 1. Check if the given Node is null */

        if (prev_node == null)

        {

            Console.WriteLine("The given previous" +

                              " node cannot be null");

            return;

        }

 

        /* 2 & 3: Allocate the Node &

                Put in the data*/

        Node new_node = new Node(new_data);

 

        /* 4. Make next of new Node as

              next of prev_node */

        new_node.next = prev_node.next;

 

        /* 5. make next of prev_node as new_node */

        prev_node.next = new_node;

    }

     

    /* Appends a new node at the end. This method is

    defined inside LinkedList class shown above */

    public void append(int new_data)

    {

        /* 1. Allocate the Node &

        2. Put in the data

        3. Set next as null */

        Node new_node = new Node(new_data);

 

        /* 4. If the Linked List is empty,

        then make the new node as head */

        if (head == null)

        {

            head = new Node(new_data);

            return;

        }

 

        /* 4. This new node is going to be the last node,

            so make next of it as null */

        new_node.next = null;

 

        /* 5. Else traverse till the last node */

        Node last = head;

        while (last.next != null)

            last = last.next;

 

        /* 6. Change the next of last node */

        last.next = new_node;

        return;

    }

 

    /* This function prints contents of linked list

    starting from the given node */

    public void printList()

    {

        Node tnode = head;

        while (tnode != null)

        {

            Console.Write(tnode.data + " ");

            tnode = tnode.next;

        }

    }

 

    // Driver Code

    public static void Main(String[] args)

    {

        /* Start with the empty list */

        GFG llist = new GFG();

 

        // Insert 6. So linked list becomes 6->NUllist

        llist.append(6);

 

        // Insert 7 at the beginning.

        // So linked list becomes 7->6->NUllist

        llist.push(7);

 

        // Insert 1 at the beginning.

        // So linked list becomes 1->7->6->NUllist

        llist.push(1);

 

        // Insert 4 at the end. So linked list becomes

        // 1->7->6->4->NUllist

        llist.append(4);

 

        // Insert 8, after 7. So linked list becomes

        // 1->7->8->6->4->NUllist

        llist.insertAfter(llist.head.next, 8);

 

        Console.Write("Created Linked list is: ");

        llist.printList();

    }

}

 

// This code is contributed by Rajput-Ji

Javascript

<script>

 

// A complete working javascript program

// to demonstrate all insertion methods

// on linked list

     var head; // head of list

 

    /* Linked list Node */

     class Node {

            constructor(val) {

                this.data = val;

                this.next = null;

            }

        }

 

    /* Inserts a new Node at front of the list. */

     function push(new_data) {

        /*

         * 1 & 2: Allocate the Node & Put in the data

         */

        var new_node = new Node(new_data);

 

        /* 3. Make next of new Node as head */

        new_node.next = head;

 

        /* 4. Move the head to point to new Node */

        head = new_node;

    }

 

    /* Inserts a new node after the given prev_node. */

     function insertAfter(prev_node , new_data) {

        /* 1. Check if the given Node is null */

        if (prev_node == null) {

            document.write(

            "The given previous node cannot be null"

            );

            return;

        }

 

        /*

         * 2 & 3: Allocate the Node & Put in the data

         */

         var new_node = new Node(new_data);

 

        /* 4. Make next of new Node as next of prev_node */

        new_node.next = prev_node.next;

 

        /* 5. make next of prev_node as new_node */

        prev_node.next = new_node;

    }

 

    /*

     * Appends a new node at the end.

       This method is defined inside LinkedList class

     * shown above

     */

     function append(new_data) {

        /*

         * 1. Allocate the Node & 2.

         Put in the data 3. Set next as null

         */

         var new_node = new Node(new_data);

 

        /*

         * 4. If the Linked List is empty,

         then make the new node as head

         */

        if (head == null) {

            head = new Node(new_data);

            return;

        }

 

        /*

         * 4. This new node is going to be the last node,

         so make next of it as null

         */

        new_node.next = null;

 

        /* 5. Else traverse till the last node */

        var last = head;

        while (last.next != null)

            last = last.next;

 

        /* 6. Change the next of last node */

        last.next = new_node;

        return;

    }

 

    /*

     * This function prints contents of linked list

     starting from the given node

     */

     function printList() {

var tnode = head;

        while (tnode != null) {

            document.write(tnode.data + " ");

            tnode = tnode.next;

        }

    }

 

    /*

     * Driver program to test above functions.

       Ideally this function should be in a

     * separate user class. It is kept here

     to keep code compact

     */

     

        /* Start with the empty list */

 

        // Insert 6. So linked list becomes 6->NUllist

        append(6);

 

        // Insert 7 at the beginning. So linked list becomes

        // 7->6->NUllist

        push(7);

 

        // Insert 1 at the beginning. So linked list becomes

        // 1->7->6->NUllist

        push(1);

 

        // Insert 4 at the end. So linked list becomes

        // 1->7->6->4->NUllist

        append(4);

 

        // Insert 8, after 7. So linked list becomes

        // 1->7->8->6->4->NUllist

        insertAfter(head.next, 8);

 

        document.write("\nCreated Linked list is: ");

        printList();

 

// This code contributed by gauravrajput1

 

</script>

Output:

 Created Linked list is:  1  7  8  6  4

The document Linked List Insertion Notes - Class 8 is a part of Class 8 category.
All you need of Class 8 at this link: Class 8

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