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# Delete a Linked List node at a given position

• Difficulty Level : Easy
• Last Updated : 27 Mar, 2023

Given a singly linked list and a position, delete a linked list node at the given position.

Example:

Input: position = 1, Linked List = 8->2->3->1->7

Input: position = 0, Linked List = 8->2->3->1->7

Approach:

If the node to be deleted is the root, simply delete it. To delete a middle node, we must have a pointer to the node previous to the node to be deleted.

#### Here are the algorithmic steps to delete a linked list node at a given position:

1. Input: A pointer to the head node of the linked list and the value to be deleted.
2. If the linked list is empty, return NULL.
3. If the node to be deleted is the head node, set the head node to the next node and delete the original head node.
4. Otherwise, traverse the linked list from the head node until the node to be deleted is found.
5. If the node to be deleted is not found, return NULL.
6. Otherwise, set the previous node’s next pointer to the node after the node to be deleted.
7. Delete the node to be deleted.

Below is the implementation of the above idea.

## C++14

 `// A complete working C++ program to delete` `// a node in a linked list at a given position` `#include ` `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)` `{` `    ``Node* new_node = ``new` `Node();` `    ``new_node->data = new_data;` `    ``new_node->next = (*head_ref);` `    ``(*head_ref) = new_node;` `}`   `// Given a reference (pointer to pointer) to` `// the head of a list and a position, deletes` `// the node at the given position` `void` `deleteNode(Node** head_ref, ``int` `position)` `{`   `    ``// If linked list is empty` `    ``if` `(*head_ref == NULL)` `        ``return``;`   `    ``// Store head node` `    ``Node* temp = *head_ref;`   `    ``// If head needs to be removed` `    ``if` `(position == 0) {`   `        ``// Change head` `        ``*head_ref = temp->next;`   `        ``// Free old head` `        ``free``(temp);` `        ``return``;` `    ``}`   `    ``// Find previous node of the node to be deleted` `    ``for` `(``int` `i = 0; temp != NULL && i < position - 1; i++)` `        ``temp = temp->next;`   `    ``// If position is more than number of nodes` `    ``if` `(temp == NULL || temp->next == NULL)` `        ``return``;`   `    ``// Node temp->next is the node to be deleted` `    ``// Store pointer to the next of node to be deleted` `    ``Node* next = temp->next->next;`   `    ``// Unlink the node from linked list` `    ``free``(temp->next); ``// Free memory`   `    ``// Unlink the deleted node from list` `    ``temp->next = next;` `}`   `// This function prints contents of linked` `// list starting from the given node` `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;`   `    ``push(&head, 7);` `    ``push(&head, 1);` `    ``push(&head, 3);` `    ``push(&head, 2);` `    ``push(&head, 8);`   `    ``cout << ``"Created Linked List: "``;` `    ``printList(head);` `    ``deleteNode(&head, 4);` `    ``cout << ``"\nLinked List after Deletion at position 4: "``;` `    ``printList(head);` `    ``return` `0;` `}`   `// This code is contributed by premsai2030`

## C

 `// Simple C code to delete node at particular position`   `#include ` `#include `   `void` `insert(``int``);` `void` `display_List();` `void` `delete` `(``int``);`   `struct` `node ``// Structure declaration` `{` `    ``int` `data;` `    ``struct` `node* next; ``// Self referral pointer` `}* head = NULL,` `   ``*tail` `   ``= NULL; ``// Initial value of Head and Tail pointer is NULL`   `void` `delete` `(``int` `pos)` `{` `    ``struct` `node* temp = head; ``// Creating a temporary` `                              ``// variable pointing to head` `    ``int` `i;` `    ``if` `(pos == 0) {` `        ``printf``(``"\nElement deleted is : %d\n"``, temp->data);` `        ``head = head->next; ``// Advancing the head pointer` `        ``temp->next = NULL;` `        ``free``(temp); ``// Node is deleted` `    ``}` `    ``else` `{` `        ``for` `(i = 0; i < pos - 1; i++) {` `            ``temp = temp->next;` `        ``}` `        ``// Now temp pointer points to the previous node of` `        ``// the node to be deleted` `        ``struct` `node* del` `            ``= temp->next; ``// del pointer points to the node` `                          ``// to be deleted` `        ``temp->next = temp->next->next;` `        ``printf``(``"\nElement deleted is : %d\n"``, del->data);` `        ``del->next = NULL;` `        ``free``(del); ``// Node is deleted` `    ``}` `    ``printf``(``"\nUpdated Linked List is : \n"``);` `    ``display_List();` `    ``return``;` `}`   `void` `insert(``int` `value)` `{` `    ``struct` `node* newnode; ``// Creating a new node` `    ``newnode = (``struct` `node*)``malloc``(` `        ``sizeof``(``struct` `node)); ``// Allocating dynamic memory`   `    ``newnode->data = value; ``// Assigning value to newnode` `    ``newnode->next = NULL;`   `    ``if` `(head == NULL) ``// Checking if List is empty` `    ``{` `        ``head = newnode;` `        ``tail = newnode;` `    ``}` `    ``else` `// If not empty then...` `    ``{` `        ``tail->next = newnode;` `        ``tail = newnode; ``// Updating the tail node with each` `                        ``// insertion` `    ``}` `    ``return``;` `}`   `void` `display_List()` `{` `    ``struct` `node* temp; ``// Creating a temporary pointer to` `                       ``// the structure` `    ``temp = head; ``// temp points to head;` `    ``while` `(temp != NULL) {` `        ``if` `(temp->next == NULL) {` `            ``printf``(``" %d->NULL"``, temp->data);` `        ``}` `        ``else` `{` `            ``printf``(``" %d->"``, temp->data);` `        ``}` `        ``temp = temp->next; ``// Traversing the List till end` `    ``}` `    ``printf``(``"\n"``);` `    ``return``;` `}` `// --Driver Code--` `int` `main()` `{` `    ``insert(10);` `    ``insert(20);` `    ``insert(30);` `    ``insert(40);` `    ``insert(50);` `    ``insert(60);` `    ``printf``(``"\n--Created Linked List--\n"``);` `    ``display_List();` `    ``printf``(``"\nLinked List after deletion at position 0"``);` `    ``delete` `(0); ``// List indexing starts from 0` `    ``printf``(``"\nLinked List after deletion at position 2"``);` `    ``delete` `(2);` `    ``return` `0;` `}` `// This code is contributed by Sanjeeban Mukhopadhyay.`

## Java

 `// A complete working Java program to delete a node in a` `// linked list at a given position` `import` `java.io.*;` `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;` `    ``}`   `    ``/* Given a reference (pointer to pointer) to the head of` `       ``a list` `       ``and a position, deletes the node at the given` `       ``position */` `    ``void` `deleteNode(``int` `position)` `    ``{` `        ``// If linked list is empty` `        ``if` `(head == ``null``)` `            ``return``;`   `        ``// Store head node` `        ``Node temp = head;`   `        ``// If head needs to be removed` `        ``if` `(position == ``0``) {` `            ``head = temp.next; ``// Change head` `            ``return``;` `        ``}`   `        ``// Find previous node of the node to be deleted` `        ``for` `(``int` `i = ``0``; temp != ``null` `&& i < position - ``1``;` `             ``i++)` `            ``temp = temp.next;`   `        ``// If position is more than number of nodes` `        ``if` `(temp == ``null` `|| temp.next == ``null``)` `            ``return``;`   `        ``// Node temp->next is the node to be deleted` `        ``// Store pointer to the next of node to be deleted` `        ``Node next = temp.next.next;`   `        ``temp.next` `            ``= next; ``// Unlink the deleted node from list` `    ``}`   `    ``/* 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();`   `        ``llist.push(``7``);` `        ``llist.push(``1``);` `        ``llist.push(``3``);` `        ``llist.push(``2``);` `        ``llist.push(``8``);`   `        ``System.out.println(``"\nCreated Linked list is: "``);` `        ``llist.printList();`   `        ``llist.deleteNode(``4``); ``// Delete node at position 4`   `        ``System.out.println(` `            ``"\nLinked List after Deletion at position 4: "``);` `        ``llist.printList();` `    ``}` `}`

## Python3

 `# Python program to delete a node in a linked list` `# at a given position`   `# Node class`     `class` `Node:`   `    ``# Constructor to initialize the node object` `    ``def` `__init__(``self``, data):` `        ``self``.data ``=` `data` `        ``self``.``next` `=` `None`     `class` `LinkedList:`   `    ``# Constructor to initialize head` `    ``def` `__init__(``self``):` `        ``self``.head ``=` `None`   `    ``# Function to insert a new node at the beginning` `    ``def` `push(``self``, new_data):` `        ``new_node ``=` `Node(new_data)` `        ``new_node.``next` `=` `self``.head` `        ``self``.head ``=` `new_node`   `    ``# Given a reference to the head of a list` `    ``# and a position, delete the node at a given position` `    ``# This delete function code is contributed by Arabin Islam` `    ``def` `deleteNodeAtGivenPosition(``self``, position):` `        ``if` `self``.head ``is` `None``:` `            ``return` `        ``index ``=` `0` `        ``current ``=` `self``.head` `        ``while` `current.``next` `and` `index < position:` `            ``previous ``=` `current` `            ``current ``=` `current.``next` `            ``index ``+``=` `1` `        ``if` `index < position:` `            ``print``(``"\nIndex is out of range."``)` `        ``elif` `index ``=``=` `0``:` `            ``self``.head ``=` `self``.head.``next` `        ``else``:` `            ``previous.``next` `=` `current.``next` `            ``# current = None #Optional statement`   `    ``# Utility function to print the LinkedList`   `    ``def` `printList(``self``):` `        ``temp ``=` `self``.head` `        ``while``(temp):` `            ``print``(``" %d "` `%` `(temp.data), end``=``" "``)` `            ``temp ``=` `temp.``next`     `# Driver program to test above function` `llist ``=` `LinkedList()` `llist.push(``7``)` `llist.push(``1``)` `llist.push(``3``)` `llist.push(``2``)` `llist.push(``8``)`   `print``(``"Created Linked List: "``)` `llist.printList()` `llist.deleteNodeAtGivenPosition(``4``)` `print``(``"\nLinked List after Deletion at position 4: "``)` `llist.printList()`   `# This code is contributed by Nikhil Kumar Singh(nickzuck_007)`

## C#

 `// A complete working C# program to delete` `// a node in a linked list at a given position` `using` `System;`   `class` `GFG {`   `    ``// Head of list` `    ``Node head;`   `    ``// 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;` `    ``}`   `    ``// Given a reference (pointer to pointer)` `    ``// to the head of a list and a position,` `    ``// deletes the node at the given position` `    ``void` `deleteNode(``int` `position)` `    ``{`   `        ``// If linked list is empty` `        ``if` `(head == ``null``)` `            ``return``;`   `        ``// Store head node` `        ``Node temp = head;`   `        ``// If head needs to be removed` `        ``if` `(position == 0) {`   `            ``// Change head` `            ``head = temp.next;` `            ``return``;` `        ``}`   `        ``// Find previous node of the node to be deleted` `        ``for` `(``int` `i = 0; temp != ``null` `&& i < position - 1;` `             ``i++)` `            ``temp = temp.next;`   `        ``// If position is more than number of nodes` `        ``if` `(temp == ``null` `|| temp.next == ``null``)` `            ``return``;`   `        ``// Node temp->next is the node to be deleted` `        ``// Store pointer to the next of node to be deleted` `        ``Node next = temp.next.next;`   `        ``// Unlink the deleted node from list` `        ``temp.next = next;` `    ``}`   `    ``// 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();`   `        ``llist.Push(7);` `        ``llist.Push(1);` `        ``llist.Push(3);` `        ``llist.Push(2);` `        ``llist.Push(8);`   `        ``Console.WriteLine(``"\nCreated Linked list is: "``);` `        ``llist.printList();`   `        ``// Delete node at position 4` `        ``llist.deleteNode(4);`   `        ``Console.WriteLine(``"\nLinked List after "` `                          ``+ ``"Deletion at position 4: "``);` `        ``llist.printList();` `    ``}` `}`   `// This code is contributed by Rajput-Ji`

## Javascript

 ``

Output

```Created Linked List: 8 2 3 1 7
Linked List after Deletion at position 4: 8 2 3 1 ```

Time Complexity:

• Best Case: O(1) if given position is 1
• Average  & Worst Case: O(N) where N is the length of the linked list. This is because in the worst case, we need to traverse the entire linked list to find the node to be deleted.

Auxiliary Space: O(1) as we are only using a constant amount of extra space for temporary variables and pointers, regardless of the size of the linked list. Specifically, we only need to allocate memory for a few temporary pointers (e.g., current, temp) and the new head pointer if the original head is deleted. The memory for the deleted node(s) is also freed as soon as it is deleted

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