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Delete a node in a Doubly Linked List
• Difficulty Level : Easy
• Last Updated : 13 May, 2021

Pre-requisite: Doubly Link List Set 1| Introduction and Insertion

Write a function to delete a given node in a doubly-linked list. Approach: The deletion of a node in a doubly-linked list can be divided into three main categories:

• After the deletion of the head node. • After the deletion of the middle node. • After the deletion of the last node. All three mentioned cases can be handled in two steps if the pointer of the node to be deleted and the head pointer is known.

1. If the node to be deleted is the head node then make the next node as head.
2. If a node is deleted, connect the next and previous node of the deleted node. Algorithm

• Let the node to be deleted be del.
• If node to be deleted is head node, then change the head pointer to next current head.
```if headnode == del then
• Set next of previous to del, if previous to del exists.
```if del.nextNode != none
del.nextNode.previousNode = del.previousNode ```
• Set prev of next to del, if next to del exists.
```if del.previousNode != none
del.previousNode.nextNode = del.next```

## C++

 `// C++ program to delete a node from``// Doubly Linked List``#include ``using` `namespace` `std;` `/* a node of the doubly linked list */``class` `Node``{``    ``public``:``    ``int` `data;``    ``Node* next;``    ``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(Node** head_ref, 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);``    ``return``;``}` `/* UTILITY FUNCTIONS */``/* Function to insert a node at the``beginning of the Doubly Linked List */``void` `push(Node** head_ref, ``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_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``This function is same as printList() of singly linked list */``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;` `    ``/* Let us create the doubly linked list 10<->8<->4<->2 */``    ``push(&head, 2);``    ``push(&head, 4);``    ``push(&head, 8);``    ``push(&head, 10);` `    ``cout << ``"Original Linked list "``;``    ``printList(head);` `    ``/* delete nodes from the doubly linked list */``    ``deleteNode(&head, head); ``/*delete first node*/``    ``deleteNode(&head, head->next); ``/*delete middle node*/``    ``deleteNode(&head, head->next); ``/*delete last node*/` `    ``/* Modified linked list will be NULL<-8->NULL */``    ``cout << ``"\nModified Linked list "``;``    ``printList(head);` `    ``return` `0;``}` `// This code is contributed by rathbhupendra`

## C

 `#include ``#include ` `/* 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);``    ``return``;``}` `/* UTILITY FUNCTIONS */``/* 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``   ``This function is same as printList() of singly linked list */``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;` `    ``/* Let us create the doubly linked list 10<->8<->4<->2 */``    ``push(&head, 2);``    ``push(&head, 4);``    ``push(&head, 8);``    ``push(&head, 10);` `    ``printf``(``"\n Original Linked list "``);``    ``printList(head);` `    ``/* delete nodes from the doubly linked list */``    ``deleteNode(&head, head); ``/*delete first node*/``    ``deleteNode(&head, head->next); ``/*delete middle node*/``    ``deleteNode(&head, head->next); ``/*delete last node*/` `    ``/* Modified linked list will be NULL<-8->NULL */``    ``printf``(``"\n Modified Linked list "``);``    ``printList(head);` `    ``getchar``();``}`

## Java

 `// Java program to delete a node from``// Doubly Linked List` `// Class for Doubly Linked List``public` `class` `DLL {``    ``Node head; ``// head of list` `    ``/* Doubly Linked list Node*/``    ``class` `Node {``        ``int` `data;``        ``Node prev;``        ``Node next;` `        ``// Constructor to create a new node``        ``// next and prev is by default initialized``        ``// as null``        ``Node(``int` `d) { data = d; }``    ``}` `    ``// Adding a node at the front of the list``    ``public` `void` `push(``int` `new_data)``    ``{``        ``// 1. allocate node``        ``// 2. put in the data``        ``Node new_Node = ``new` `Node(new_data);` `        ``// 3. Make next of new node as head``        ``// and previous as NULL``        ``new_Node.next = head;``        ``new_Node.prev = ``null``;` `        ``// 4. change prev of head node to new node``        ``if` `(head != ``null``)``            ``head.prev = new_Node;` `        ``// 5. move the head to point to the new node``        ``head = new_Node;``    ``}` `    ``// This function prints contents of linked list``    ``// starting from the given node``    ``public` `void` `printlist(Node node)``    ``{``        ``Node last = ``null``;` `        ``while` `(node != ``null``) {``            ``System.out.print(node.data + ``" "``);``            ``last = node;``            ``node = node.next;``        ``}` `        ``System.out.println();``    ``}` `    ``// Function to delete a node in a Doubly Linked List.``    ``// head_ref --> pointer to head node pointer.``    ``// del --> data of node to be deleted.``    ``void` `deleteNode(Node del)``    ``{` `        ``// Base case``        ``if` `(head == ``null` `|| del == ``null``) {``            ``return``;``        ``}` `        ``// 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;``        ``}` `        ``// Finally, free the memory occupied by del``        ``return``;``    ``}` `    ``// Driver Code``    ``public` `static` `void` `main(String[] args)``    ``{``        ``// Start with the empty list``        ``DLL dll = ``new` `DLL();` `        ``// Insert 2. So linked list becomes 2->NULL``        ``dll.push(``2``);` `        ``// Insert 4. So linked list becomes 4->2->NULL``        ``dll.push(``4``);` `        ``// Insert 8. So linked list becomes 8->4->2->NULL``        ``dll.push(``8``);` `        ``// Insert 10. So linked list becomes 10->8->4->2->NULL``        ``dll.push(``10``);` `        ``System.out.print(``"Created DLL is: "``);``        ``dll.printlist(dll.head);` `        ``// Deleting first node``        ``dll.deleteNode(dll.head);` `        ``// List after deleting first node``        ``// 8->4->2``        ``System.out.print(``"\nList after deleting first node: "``);``        ``dll.printlist(dll.head);` `        ``// Deleting middle node from 8->4->2``        ``dll.deleteNode(dll.head.next);` `        ``System.out.print(``"\nList after Deleting middle node: "``);``        ``dll.printlist(dll.head);``    ``}``}`

## Python

 `# Program to delete a node in a doubly-linked list` `# for Garbage collection``import` `gc` `# A node of the doublly linked list``class` `Node:``    ` `    ``# Constructor to create a new node``    ``def` `__init__(``self``, data):``        ``self``.data ``=` `data``        ``self``.``next` `=` `None``        ``self``.prev ``=` `None` `class` `DoublyLinkedList:``     ``# Constructor for empty Doubly Linked List``    ``def` `__init__(``self``):``        ``self``.head ``=` `None`` ` `   ``# Function to delete a node in a Doubly Linked List.``   ``# head_ref --> pointer to head node pointer.``   ``# dele --> pointer to node to be deleted` `    ``def` `deleteNode(``self``, dele):``        ` `        ``# Base Case``        ``if` `self``.head ``is` `None` `or` `dele ``is` `None``:``            ``return``        ` `        ``# If node to be deleted is head node``        ``if` `self``.head ``=``=` `dele:``            ``self``.head ``=` `dele.``next` `        ``# Change next only if node to be deleted is NOT``        ``# the last node``        ``if` `dele.``next` `is` `not` `None``:``            ``dele.``next``.prev ``=` `dele.prev``    ` `        ``# Change prev only if node to be deleted is NOT``        ``# the first node``        ``if` `dele.prev ``is` `not` `None``:``            ``dele.prev.``next` `=` `dele.``next``        ``# Finally, free the memory occupied by dele``        ``# Call python garbage collector``        ``gc.collect()`  `    ``# Given a reference to the head of a list and an``    ``# integer, inserts a new node on the front of list``    ``def` `push(``self``, new_data):`` ` `        ``# 1. Allocates node``        ``# 2. Put the data in it``        ``new_node ``=` `Node(new_data)`` ` `        ``# 3. Make next of new node as head and``        ``# previous as None (already None)``        ``new_node.``next` `=` `self``.head`` ` `        ``# 4. change prev of head node to new_node``        ``if` `self``.head ``is` `not` `None``:``            ``self``.head.prev ``=` `new_node`` ` `        ``# 5. move the head to point to the new node``        ``self``.head ``=` `new_node`  `    ``def` `printList(``self``, node):``        ``while``(node ``is` `not` `None``):``            ``print` `node.data,``            ``node ``=` `node.``next`  `# Driver program to test the above functions` `# Start with empty list``dll ``=` `DoublyLinkedList()` `# Let us create the doubly linked list 10<->8<->4<->2``dll.push(``2``);``dll.push(``4``);``dll.push(``8``);``dll.push(``10``);` `print` `"\n Original Linked List"``,``dll.printList(dll.head)` `# delete nodes from doubly linked list``dll.deleteNode(dll.head)``dll.deleteNode(dll.head.``next``)``dll.deleteNode(dll.head.``next``)``# Modified linked list will be NULL<-8->NULL``print` `"\n Modified Linked List"``,``dll.printList(dll.head)` `# This code is contributed by Nikhil Kumar Singh(nickzuck_007)`

## C#

 `// C# program to delete a node from``// Doubly Linked List``using` `System;` `// Class for Doubly Linked List``public` `class` `DLL``{``    ``Node head; ``// head of list` `    ``/* Doubly Linked list Node*/``    ``public` `class` `Node``    ``{``        ``public` `int` `data;``        ``public` `Node prev;``        ``public` `Node next;` `        ``// Constructor to create a new node``        ``// next and prev is by default``        ``// initialized as null``        ``public` `Node(``int` `d) { data = d; }``    ``}` `    ``// Adding a node at the front of the list``    ``public` `void` `push(``int` `new_data)``    ``{``        ``// 1. allocate node``        ``// 2. put in the data``        ``Node new_Node = ``new` `Node(new_data);` `        ``// 3. Make next of new node as head``        ``// and previous as NULL``        ``new_Node.next = head;``        ``new_Node.prev = ``null``;` `        ``// 4. change prev of head node to new node``        ``if` `(head != ``null``)``            ``head.prev = new_Node;` `        ``// 5. move the head to point to the new node``        ``head = new_Node;``    ``}` `    ``// This function prints contents of linked list``    ``// starting from the given node``    ``public` `void` `printlist(Node node)``    ``{` `        ``while` `(node != ``null``)``        ``{``            ``Console.Write(node.data + ``" "``);``            ``node = node.next;``        ``}` `        ``Console.WriteLine();``    ``}` `    ``// Function to delete a node in a Doubly Linked List.``    ``// head_ref --> pointer to head node pointer.``    ``// del --> data of node to be deleted.``    ``void` `deleteNode(Node del)``    ``{` `        ``// Base case``        ``if` `(head == ``null` `|| del == ``null``)``        ``{``            ``return``;``        ``}` `        ``// 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;``        ``}` `        ``// Finally, free the memory occupied by del``        ``return``;``    ``}` `    ``// Driver Code``    ``public` `static` `void` `Main()``    ``{``        ``// Start with the empty list``        ``DLL dll = ``new` `DLL();` `        ``// Insert 2. So linked list becomes 2->NULL``        ``dll.push(2);` `        ``// Insert 4. So linked list becomes 4->2->NULL``        ``dll.push(4);` `        ``// Insert 8. So linked list becomes 8->4->2->NULL``        ``dll.push(8);` `        ``// Insert 10. So linked list becomes 10->8->4->2->NULL``        ``dll.push(10);` `        ``Console.Write(``"Created DLL is: "``);``        ``dll.printlist(dll.head);` `        ``// Deleting first node``        ``dll.deleteNode(dll.head);` `        ``// List after deleting first node``        ``// 8->4->2``        ``Console.Write(``"\nList after deleting first node: "``);``        ``dll.printlist(dll.head);` `        ``// Deleting middle node from 8->4->2``        ``dll.deleteNode(dll.head.next);` `        ``Console.Write(``"\nList after Deleting middle node: "``);``        ``dll.printlist(dll.head);``    ``}``}``// This code is contributed by PrinciRaj1992`

## Javascript

 ``
Output:
```Original Linked list 10 8 4 2

Complexity Analysis:

• Time Complexity: O(1).
Since traversal of the linked list is not required so the time complexity is constant.
• Space Complexity: O(1).
As no extra space is required, so the space complexity is constant.

Please write comments if you find any of the above codes/algorithms incorrect, or find better ways to solve the same problem.

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