Skip to content
Related Articles

Related Articles

Improve Article

Delete a Doubly Linked List node at a given position

  • Difficulty Level : Basic
  • Last Updated : 23 May, 2021

Given a doubly linked list and a position n. The task is to delete the node at the given position n from the beginning.
Initial doubly linked list
 

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

Doubly Linked List after deletion of node at position n = 2
 



Approach: Following are the steps:

  1. Get the pointer to the node at position n by traversing the doubly linked list up to the nth node from the beginning.
  2. Delete the node using the pointer obtained in Step 1. Refer this post.

C++




/* C++ implementation to delete a doubly Linked List node
   at the given position */
#include <bits/stdc++.h>
 
using namespace std;
 
/* a node of the doubly linked list */
struct Node {
    int data;
    struct Node* next;
    struct Node* prev;
};
 
/* Function to delete a node in a Doubly Linked List.
   head_ref --> pointer to head node pointer.
   del  -->  pointer to node to be deleted. */
void deleteNode(struct Node** head_ref, struct Node* del)
{
    /* base case */
    if (*head_ref == NULL || del == NULL)
        return;
 
    /* If node to be deleted is head node */
    if (*head_ref == del)
        *head_ref = del->next;
 
    /* Change next only if node to be deleted is NOT
       the last node */
    if (del->next != NULL)
        del->next->prev = del->prev;
 
    /* Change prev only if node to be deleted is NOT
       the first node */
    if (del->prev != NULL)
        del->prev->next = del->next;
 
    /* Finally, free the memory occupied by del*/
    free(del);
}
 
/* Function to delete the node at the given position
   in the doubly linked list */
void deleteNodeAtGivenPos(struct Node** head_ref, int n)
{
    /* if list in NULL or invalid position is given */
    if (*head_ref == NULL || n <= 0)
        return;
 
    struct Node* current = *head_ref;
    int i;
 
    /* traverse up to the node at position 'n' from
       the beginning */
    for (int i = 1; current != NULL && i < n; i++)
        current = current->next;
 
    /* if 'n' is greater than the number of nodes
       in the doubly linked list */
    if (current == NULL)
        return;
 
    /* delete the node pointed to by 'current' */
    deleteNode(head_ref, current);
}
 
/* Function to insert a node at the beginning
   of the Doubly Linked List */
void push(struct Node** head_ref, int new_data)
{
    /* allocate node */
    struct Node* new_node =
         (struct Node*)malloc(sizeof(struct Node));
 
    /* put in the data  */
    new_node->data = new_data;
 
    /* since we are adding at the beginning,
    prev is always NULL */
    new_node->prev = NULL;
 
    /* link the old list off the new node */
    new_node->next = (*head_ref);
 
    /* change prev of head node to new node */
    if ((*head_ref) != NULL)
        (*head_ref)->prev = new_node;
 
    /* move the head to point to the new node */
    (*head_ref) = new_node;
}
 
/* Function to print nodes in a given doubly
   linked list */
void printList(struct Node* head)
{
    while (head != NULL) {
        cout << head->data << " ";
        head = head->next;
    }
}
 
/* Driver program to test above functions*/
int main()
{
    /* Start with the empty list */
    struct Node* head = NULL;
 
    /* Create the doubly linked list 10<->8<->4<->2<->5 */
    push(&head, 5);
    push(&head, 2);
    push(&head, 4);
    push(&head, 8);
    push(&head, 10);
 
    cout << "Doubly linked list before deletion:n";
    printList(head);
 
    int n = 2;
 
    /* delete node at the given position 'n' */
    deleteNodeAtGivenPos(&head, n);
 
    cout << "\nDoubly linked list after deletion:n";
    printList(head);
 
    return 0;
}

Java




/* Java implementation to delete a
   doubly Linked List node
   at the given position */
    
// A node of the doubly linked list
class Node
{
    int data;
    Node next, prev;
}
 
class GFG
{
    static Node head = null;
    // Function to delete a node
    // in a Doubly Linked List.
    // head_ref --> pointer to head node pointer.
    // del --> pointer to node to be deleted.
    static Node deleteNode(Node del)
    {
        // base case
        if (head == null || del == null)
            return null;
 
        // If node to be deleted is head node
        if (head == del)
            head = del.next;
 
        // Change next only if node to be
        // deleted is NOT the last node
        if (del.next != null)
            del.next.prev = del.prev;
 
        // Change prev only if node to be
        // deleted is NOT the first node
        if (del.prev != null)
            del.prev.next = del.next;
 
        del = null;
 
        return head;
    }
 
    // Function to delete the node at the
    // given position in the doubly linked list
    static void deleteNodeAtGivenPos(int n)
    {
        /* if list in NULL or
          invalid position is given */
        if (head == null || n <= 0)
            return;
 
        Node current = head;
        int i;
 
        /*
        * traverse up to the node at
          position 'n' from the beginning
        */
        for (i = 1; current != null && i < n; i++)
        {
            current = current.next;
        }
         
        // if 'n' is greater than the number of nodes
        // in the doubly linked list
        if (current == null)
            return;
 
        // delete the node pointed to by 'current'
        deleteNode(current);
    }
 
    // Function to insert a node
    // at the beginning of the Doubly Linked List
    static void push(int new_data)
    {
        // allocate node
        Node new_node = new Node();
 
        // put in the data
        new_node.data = new_data;
 
        // since we are adding at the beginning,
        // prev is always NULL
 
        new_node.prev = null;
 
        // link the old list off the new node
        new_node.next = head;
 
        // change prev of head node to new node
        if (head != null)
            head.prev = new_node;
 
        // move the head to point to the new node
        head = new_node;
    }
 
    // Function to print nodes in a
    // given doubly linked list
    static void printList()
    {
        Node temp = head;
        if (temp == null)
            System.out.print("Doubly Linked list empty");
 
        while (temp != null)
        {
            System.out.print(temp.data + " ");
            temp = temp.next;
        }
        System.out.println();
    }
 
    // Driver code
    public static void main(String[] args)
    {
        // Create the doubly linked list:
        // 10<->8<->4<->2<->5
 
        push(5);
        push(2);
        push(4);
        push(8);
        push(10);
 
        System.out.println("Doubly linked "
                           +"list before deletion:");
        printList();
 
        int n = 2;
         
        // delete node at the given position 'n'
        deleteNodeAtGivenPos(n);
        System.out.println("Doubly linked "
                           +"list after deletion:");
        printList();
    }
}
 
// Thia code is contributed by Vivekkumar Singh

Python




# Python implementation to delete
# a doubly Linked List node
# at the given position
 
# A node of the doubly linked list
class Node:
     
    # Constructor to create a new node
    def __init__(self, data):
        self.data = data
        self.next = None
        self.prev = None
 
# Function to delete a node in a Doubly Linked List.
# head_ref -. pointer to head node pointer.
# del -. pointer to node to be deleted.
def deleteNode(head_ref, del_):
 
    # base case
    if (head_ref == None or del_ == None):
        return
 
    # If node to be deleted is head node
    if (head_ref == del_):
        head_ref = del_.next
 
    # Change next only if node to be deleted is NOT
    # the last node
    if (del_.next != None):
        del_.next.prev = del_.prev
 
    # Change prev only if node to be deleted is NOT
    # the first node
    if (del_.prev != None):
        del_.prev.next = del_.next
         
    return head_ref
 
# Function to delete the node at the given position
# in the doubly linked list
def deleteNodeAtGivenPos(head_ref,n):
 
    # if list in None or invalid position is given
    if (head_ref == None or n <= 0):
        return
 
    current = head_ref
    i = 1
 
    # traverse up to the node at position 'n' from
    # the beginning
    while ( current != None and i < n ):
        current = current.next
        i = i + 1
 
    # if 'n' is greater than the number of nodes
    # in the doubly linked list
    if (current == None):
        return
 
    # delete the node pointed to by 'current'
    deleteNode(head_ref, current)
     
    return head_ref
 
# Function to insert a node at the beginning
# of the Doubly Linked List
def push(head_ref, new_data):
 
    # allocate node
    new_node = Node(0)
 
    # put in the data
    new_node.data = new_data
 
    # since we are adding at the beginning,
    #prev is always None
    new_node.prev = None
 
    # link the old list off the new node
    new_node.next = (head_ref)
 
    # change prev of head node to new node
    if ((head_ref) != None):
        (head_ref).prev = new_node
 
    # move the head to point to the new node
    (head_ref) = new_node
     
    return head_ref
 
# Function to print nodes in a given doubly
# linked list
def printList(head):
 
    while (head != None) :
        print( head.data ,end= " ")
        head = head.next
     
# Driver program to test above functions
 
# Start with the empty list
head = None
 
# Create the doubly linked list 10<.8<.4<.2<.5
head = push(head, 5)
head = push(head, 2)
head = push(head, 4)
head = push(head, 8)
head = push(head, 10)
 
print("Doubly linked list before deletion:")
printList(head)
 
n = 2
 
# delete node at the given position 'n'
head = deleteNodeAtGivenPos(head, n)
 
print("\nDoubly linked list after deletion:")
 
printList(head)
 
# This code is contributed by Arnab Kundu

C#




/* C# implementation to delete a doubly Linked List node
at the given position */
using System;
 
// A node of the doubly linked list
public class Node
{
    public int data;
    public Node next, prev;
}
 
class GFG
{
    // Function to delete a node in a Doubly Linked List.
    // head_ref --> pointer to head node pointer.
    // del --> pointer to node to be deleted.
    static Node deleteNode(Node head, Node del)
    {
        // base case
        if (head == null || del == null)
            return null;
 
        // If node to be deleted is head node
        if (head == del)
            head = del.next;
 
        // Change next only if node to be
        // deleted is NOT the last node
        if (del.next != null)
            del.next.prev = del.prev;
 
        // Change prev only if node to be
        // deleted is NOT the first node
        if (del.prev != null)
            del.prev.next = del.next;
 
        del = null;
 
        return head;
    }
 
    // Function to delete the node at the
    // given position in the doubly linked list
    static void deleteNodeAtGivenPos(Node head, int n)
    {
        /* if list in NULL or invalid position is given */
        if (head == null || n <= 0)
            return;
 
        Node current = head;
        int i;
 
        /*
        * traverse up to the node at position 'n' from the beginning
        */
        for (i = 1; current != null && i < n; i++)
        {
            current = current.next;
        }
         
        // if 'n' is greater than the number of nodes
        // in the doubly linked list
        if (current == null)
            return;
 
        // delete the node pointed to by 'current'
        deleteNode(head, current);
    }
 
    // Function to insert a node
    // at the beginning of the Doubly Linked List
    static Node push(Node head, int new_data)
    {
        // allocate node
        Node new_node = new Node();
 
        // put in the data
        new_node.data = new_data;
 
        // since we are adding at the beginning,
        // prev is always NULL
 
        new_node.prev = null;
 
        // link the old list off the new node
        new_node.next = head;
 
        // change prev of head node to new node
        if (head != null)
            head.prev = new_node;
 
        // move the head to point to the new node
        head = new_node;
 
        return head;
    }
 
    // Function to print nodes in a
    // given doubly linked list
    static void printList(Node temp)
    {
        if (temp == null)
            Console.Write("Doubly Linked list empty");
 
        while (temp != null)
        {
            Console.Write(temp.data + " ");
            temp = temp.next;
        }
        Console.WriteLine();
    }
 
    // Driver code
    public static void Main(String []args)
    {
        // Start with the empty list
        Node head = null;
 
        // Create the doubly linked list:
        // 2<->2<->10<->8<->4<->2<->5<->2
 
        head = push(head, 2);
        head = push(head, 5);
        head = push(head, 4);
        head = push(head, 8);
        head = push(head, 10);
 
        Console.WriteLine("Doubly linked list before deletion:");
        printList(head);
 
        int n = 2;
         
        // delete node at the given position 'n'
        deleteNodeAtGivenPos(head, n);
        Console.WriteLine("Doubly linked list after deletion:");
        printList(head);
    }
}
 
// This code is contributed by Arnab Kundu

Javascript




<script>
/* javascript implementation to delete a
   doubly Linked List node
   at the given position */
 
// A node of the doubly linked list
class Node {
        constructor() {
            this.data = 0;
            this.prev = null;
            this.next = null;
        }
    }
var head = null;
 
    // Function to delete a node
    // in a Doubly Linked List.
    // head_ref --> pointer to head node pointer.
    // del --> pointer to node to be deleted.
    function deleteNode(del) {
        // base case
        if (head == null || del == null)
            return null;
 
        // If node to be deleted is head node
        if (head == del)
            head = del.next;
 
        // Change next only if node to be
        // deleted is NOT the last node
        if (del.next != null)
            del.next.prev = del.prev;
 
        // Change prev only if node to be
        // deleted is NOT the first node
        if (del.prev != null)
            del.prev.next = del.next;
 
        del = null;
 
        return head;
    }
 
    // Function to delete the node at the
    // given position in the doubly linked list
    function deleteNodeAtGivenPos(n) {
        /*
         * if list in NULL or invalid position is given
         */
        if (head == null || n <= 0)
            return;
 
var current = head;
        var i;
 
        /*
         * traverse up to the node at position 'n' from the beginning
         */
        for (i = 1; current != null && i < n; i++) {
            current = current.next;
        }
 
        // if 'n' is greater than the number of nodes
        // in the doubly linked list
        if (current == null)
            return;
 
        // delete the node pointed to by 'current'
        deleteNode(current);
    }
 
    // Function to insert a node
    // at the beginning of the Doubly Linked List
    function push(new_data) {
        // allocate node
var new_node = new Node();
 
        // put in the data
        new_node.data = new_data;
 
        // since we are adding at the beginning,
        // prev is always NULL
 
        new_node.prev = null;
 
        // link the old list off the new node
        new_node.next = head;
 
        // change prev of head node to new node
        if (head != null)
            head.prev = new_node;
 
        // move the head to povar to the new node
        head = new_node;
    }
 
    // Function to prvar nodes in a
    // given doubly linked list
    function printList() {
var temp = head;
        if (temp == null)
            document.write("Doubly Linked list empty");
 
        while (temp != null) {
            document.write(temp.data + " ");
            temp = temp.next;
        }
        document.write();
    }
 
    // Driver code
     
        // Create the doubly linked list:
        // 10<->8<->4<->2<->5
 
        push(5);
        push(2);
        push(4);
        push(8);
        push(10);
 
        document.write("Doubly linked " + "list before deletion:<br/>");
        printList();
 
        var n = 2;
 
        // delete node at the given position 'n'
        deleteNodeAtGivenPos(n);
        document.write("<br/>Doubly linked " + "list after deletion:<br/>");
        printList();
 
// This code contributed by gauravrajput1
</script>

Output: 

Doubly linked list before deletion:
10 8 4 2 5
Doubly linked list after deletion:
10 4 2 5

Time Complexity: O(n), in the worst case where n is the number of nodes in the doubly linked list.

This article is contributed by Ayush Jauhari. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.




My Personal Notes arrow_drop_up
Recommended Articles
Page :