Delete a Doubly Linked List node at a given position

Read

Discuss

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

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

Approach: Following are the steps:

Get the pointer to the node at position n by traversing the doubly linked list up to the nth node from the beginning.
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 of 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 of 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 of 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 of 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 of 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
    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:n10 8 4 2 5 
Doubly linked list after deletion:n10 4 2 5

Time Complexity: O(n), in the worst case where n is the number of nodes in the doubly linked list.
Auxiliary Space: O(1) because using constant space

If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Recommended

Solve DSA problems on GfG Practice.

Solve Problems

Feeling lost in the world of random DSA topics, wasting time without progress? It's time for a change! Join our DSA course, where we'll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 geeks!

Last Updated : 24 Jan, 2023

Delete a Doubly Linked List node at a given position

C++

Java

Python

C#

Javascript

Please Login to comment...