Deletion at beginning (Removal of first node) in a Linked List

Last Updated : 30 Aug, 2024

Given a linked list, The task is to remove the first node from the given linked list.

Examples:

Input : head : 3 -> 12 -> 15 -> 18 -> NULL
Output : 12 -> 15 -> 18 -> NULL
Input : head : 2 -> 4 -> 6 -> 8 -> 33 -> 67 -> NULL
Output : 4 -> 6 -> 8 -> 33 -> 67 -> NULL

By Shifting head node to next node of head - O(1) Time and O(1) Space

To remove the first node of a linked list, store the current head in a temporary variable (temp), move the head pointer to the next node, delete the temporary head node and finally , return the new head of the linked list.

Deletion-at-beginning- — Deletion at beginning in a Linked List

Below is the implementation of the above approach:

C++

// C++ program to delete the head node  // from a linked list #include <iostream> using namespace std; struct Node {  int data;  Node *next;  Node(int x) {  data = x;  next = nullptr;  } }; // Delete the head node and return the new head Node* deleteHead(Node* head) {    // Check if the list is empty  if (head == nullptr)  return nullptr;  // Store the current head in a  // temporary variable  Node* temp = head;  // Move the head pointer to the next node  head = head->next;  // Free the memory of the old head node  delete temp;  return head; } void printList(Node* curr) {  while (curr != nullptr) {  cout << curr->data << " ";  curr = curr->next;   } } int main() {    // Create a hard-coded linked list:  // 3 -> 12 -> 15 -> 18  Node* head = new Node(3);  head->next = new Node(12);  head->next->next = new Node(15);  head->next->next->next = new Node(18);  head = deleteHead(head);  printList(head);  return 0; }

// C program to delete the head node // from a linked list #include <stdio.h> #include <stdlib.h> struct Node {  int data;  struct Node* next; }; // Delete the head node and return the new head struct Node* deleteHead(struct Node* head) {    // Check if the list is empty  if (head == NULL)  return NULL;  // Store the current head in a   // temporary variable  struct Node* temp = head;  // Move the head pointer to the next node  head = head->next;  // Free the memory of the old head node  free(temp);  return head; } void printList(struct Node* curr) {    while (curr != NULL) {  printf("%d ", curr->data);  curr = curr->next;  } } struct Node *createNode(int new_data){  struct Node *new_node =  (struct Node *)malloc(sizeof(struct Node));  new_node->data = new_data;  new_node->next = NULL;  return new_node; } int main() {    // Create a hard-coded linked list:  // 3 -> 12 -> 15 -> 18  struct Node* head = createNode(3);  head->next = createNode(12);  head->next->next = createNode(15);  head->next->next->next = createNode(18);  head = deleteHead(head);  printList(head);  return 0; }

Java

// Java program to delete the head node // from a linked list class Node {  int data;  Node next;  Node(int data) {  this.data = data;  this.next = null;  } } public class GfG {  // Delete the head node and return the new head  static Node deleteHead(Node head) {    // Check if the list is empty  if (head == null)  return null;  // Store the current head in a temporary variable  Node temp = head;  // Move the head pointer to the next node  head = head.next;  // Help the garbage collector by   // removing the reference  temp = null;  return head;  }  static void printList(Node curr) {  while (curr != null) {  System.out.print(curr.data + " ");  curr = curr.next;  }  }  public static void main(String[] args) {    // Create a hard-coded linked list:  // 3 -> 12 -> 15 -> 18  Node head = new Node(3);  head.next = new Node(12);  head.next.next = new Node(15);  head.next.next.next = new Node(18);  head = deleteHead(head);  printList(head);  } }

Python

# Python program to delete the head node  # from a linked list class Node: def __init__(self, data): self.data = data self.next = None # Delete the head node and return the new head def delete_head(head): # Check if the list is empty if head is None: return None # Store the current head in a temporary variable temp = head # Move the head pointer to the next node head = head.next # Delete the old head by removing the reference del temp return head def print_list(curr): while curr: print(curr.data, end=" ") curr = curr.next if __name__ == "__main__": # Create a hard-coded linked list: # 3 -> 12 -> 15 -> 18 head = Node(3) head.next = Node(12) head.next.next = Node(15) head.next.next.next = Node(18) head = delete_head(head) print_list(head)

// C# program to delete the head node // from a linked list using System; class Node {  public int data;  public Node next;  public Node(int data) {  this.data = data;  this.next = null;  } } class GfG {  // Delete the head node and return the new head  static Node DeleteHead(Node head) {    // Check if the list is empty  if (head == null)  return null;  // Move the head pointer to the next node  head = head.next;  return head;  }  static void PrintList(Node curr) {  while (curr != null) {  Console.Write(curr.data + " ");  curr = curr.next;  }  }  static void Main() {    // Create a hard-coded linked list:  // 3 -> 12 -> 15 -> 18  Node head = new Node(3);  head.next = new Node(12);  head.next.next = new Node(15);  head.next.next.next = new Node(18);  head = DeleteHead(head);  PrintList(head);  } }

JavaScript

// JavaScript program to delete the head //node from a linked list class Node {  constructor(data) {  this.data = data;  this.next = null;  } } // Delete the head node and return the new head function deleteHead(head) {  // Check if the list is empty  if (head === null)  return null;  // Store the current head in a temporary variable  let temp = head;  // Move the head pointer to the next node  head = head.next;  // Free the memory of the old head node  temp = null;  return head; } function printList(curr) {  while (curr !== null) {  console.log(curr.data + " ");  curr = curr.next;  } } // Create a hard-coded linked list: // 3 -> 12 -> 15 -> 18 let head = new Node(3); head.next = new Node(12); head.next.next = new Node(15); head.next.next.next = new Node(18); head = deleteHead(head); printList(head);