How do you delete a node in a linked list Python?

Delete a Linked List node at a given position

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

Table of Contents Show

• Delete a Linked List node at a given position
• Delete Node in a Linked List in Python
• Prerequisites

Example:

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

Recommended: Please solve it on “PRACTICE” first, before moving on to the solution.

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. So if positions are not zero, we run a loop position-1 times and get a pointer to the previous node.

Below is the implementation of the above idea.

C++

// A complete working C++ program to delete // a node in a linked list at a given position #include <iostream> 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

// A complete working C program to delete a node in a linked // list at a given position #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) { struct Node* new_node = (struct Node*)malloc(sizeof(struct 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(struct Node** head_ref, int position) { // If linked list is empty if (*head_ref == NULL) return; // Store head node struct Node* temp = *head_ref; // If head needs to be removed if (position == 0) { *head_ref = temp->next; // Change head free(temp); // free old 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 struct Node* next = temp->next->next; // Unlink the node from linked list free(temp->next); // Free memory temp->next = next; // Unlink the deleted node from list } // This function prints contents of linked list starting // from the given node 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; push(&head, 7); push(&head, 1); push(&head, 3); push(&head, 2); push(&head, 8); puts("Created Linked List: "); printList(head); deleteNode(&head, 4); puts("\nLinked List after Deletion at position 4: "); printList(head); return 0; }

Java

// A complete working Java program to delete a node in a // linked list at a given position 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 deleteNode(self, position): if self.head is None: return if position == 0: self.head = self.head.next return self.head index = 0 current = self.head prev = self.head temp = self.head while current is not None: if index == position: temp = current.next break prev = current current = current.next index += 1 prev.next = temp return prev # Utility function to print the linked 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.deleteNode(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

<script> // A complete working javascript program to // delete a node in a linked list at a // given position // head of list var head; /* 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; } /* * Given a reference (pointer to pointer) to the * head of a list and a position, * deletes the node at the given position */ function deleteNode(position) { // If linked list is empty if (head == null) return; // Store head node var 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(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 var 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 */ 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 */ push(7); push(1); push(3); push(2); push(8); document.write("Created Linked list is: <br/>"); printList(); // Delete node at position 4 deleteNode(4); document.write("<br/>Linked List after " + "Deletion at position 4: <br/>"); printList(); // This code is contributed by todaysgaurav </script>

Output:

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

Thanks to Hemanth Kumar for suggesting initial solution. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above

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Linked List

Delete Node in a Linked List in Python

Suppose we have a linked list with few elements. Our task is to write a function that will delete the given node from the list. So if the list is like 1 → 3 → 5 → 7 → 9, and after deleting 3, it will be 1 → 5 → 7 → 9.

Consider we have the pointer ‘node’ to point that node to be deleted, we have to perform these operations to delete the node −

• node.val = node.next.val
• node.next = node.next.next

Prerequisites

To learn about singly linked lists, you should know:

1. Python 3
2. OOP concepts
3. Singly linked list - inserting a node and printing the nodes