Remove first node of the linked list
Given a linked list, the task is to remove the first node of the linked list and update the head pointer of the linked list.
Examples:
Input : 1 -> 2 -> 3 -> 4 -> 5 -> NULL Output : 2 -> 3 -> 4 -> 5 -> NULL Input : 2 -> 4 -> 6 -> 8 -> 33 -> 67 -> NULL Output : 4 -> 6 -> 8 -> 33 -> 67 -> NULL
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To remove first node, we need to make second node as head and delete memory allocated for first node.
C++
// CPP program to remove first node of// linked list.#include <iostream>using namespace std;/* Link list node */struct Node { int data; struct Node* next;};/* Function to remove the first node of the linked list */Node* removeFirstNode(struct Node* head){ if (head == NULL) return NULL; // Move the head pointer to the next node Node* temp = head; head = head->next; delete temp; return head;}// Function to push node at headvoid push(struct Node** head_ref, int new_data){ struct Node* new_node = new Node; new_node->data = new_data; new_node->next = (*head_ref); (*head_ref) = new_node;}// Driver codeint main(){ /* Start with the empty list */ Node* head = NULL; /* Use push() function to construct the below list 8 -> 23 -> 11 -> 29 -> 12 */ push(&head, 12); push(&head, 29); push(&head, 11); push(&head, 23); push(&head, 8); head = removeFirstNode(head); for (Node* temp = head; temp != NULL; temp = temp->next) cout << temp->data << " "; return 0;} |
Java
// Java program to remove first node of// linked list.class GFG { // Link list node / static class Node { int data; Node next; }; // Function to remove the first node // of the linked list / static Node removeFirstNode(Node head) { if (head == null) return null; // Move the head pointer to the next node Node temp = head; head = head.next; return head; } // Function to push node at head static Node 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; return head_ref; } // Driver code public static void main(String args[]) { // Start with the empty list / Node head = null; // Use push() function to con // the below list 8 . 23 . 11 . 29 . 12 / head = push(head, 12); head = push(head, 29); head = push(head, 11); head = push(head, 23); head = push(head, 8); head = removeFirstNode(head); for (Node temp = head; temp != null; temp = temp.next) System.out.print(temp.data + " "); }}// This code is contributed by Arnab Kundu |
Python3
# Python3 program to remove first node of # linked list.import sys# Link list nodeclass Node: def __init__(self, data): self.data = data self.next = None# Function to remove the first node # of the linked listdef removeFirstNode(head): if not head: return None temp = head # Move the head pointer to the next node head = head.next temp = None return head# Function to push node at headdef push(head, data): if not head: return Node(data) temp = Node(data) temp.next = head head = temp return head# Driver codeif __name__=='__main__': # Start with the empty list head = None # Use push() function to construct # the below list 8 -> 23 -> 11 -> 29 -> 12 head = push(head, 12) head = push(head, 29) head = push(head, 11) head = push(head, 23) head = push(head, 8) head = removeFirstNode(head) while(head): print("{} ".format(head.data), end ="") head = head.next# This code is Contributed by Vikash Kumar 37 |
C#
// C# program to remove first node of// linked list.using System;class GFG{ // Link list node / public class Node { public int data; public Node next; }; // Function to remove the first node // of the linked list / static Node removeFirstNode(Node head) { if (head == null) return null; // Move the head pointer to the next node Node temp = head; head = head.next; return head; } // Function to push node at head static Node 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; return head_ref; } // Driver code public static void Main(String []args) { // Start with the empty list / Node head = null; // Use push() function to con // the below list 8 . 23 . 11 . 29 . 12 / head = push(head, 12); head = push(head, 29); head = push(head, 11); head = push(head, 23); head = push(head, 8); head = removeFirstNode(head); for (Node temp = head; temp != null; temp = temp.next) Console.Write(temp.data + " "); }}/* This code contributed by PrinciRaj1992 */ |
Javascript
<script>// javascript program to remove first node of// linked list. // Link list node /class Node { constructor(val) { this.data = val; this.next = null; }} // Function to remove the first node // of the linked list / function removeFirstNode( head) { if (head == null) return null; // Move the head pointer to the next node temp = head; head = head.next; return head; } // Function to push node at head function push( head_ref , new_data) { new_node = new Node(); new_node.data = new_data; new_node.next = (head_ref); (head_ref) = new_node; return head_ref; } // Driver code // Start with the empty list / head = null; // Use push() function to con // the below list 8 . 23 . 11 . 29 . 12 / head = push(head, 12); head = push(head, 29); head = push(head, 11); head = push(head, 23); head = push(head, 8); head = removeFirstNode(head); for ( temp = head; temp != null; temp = temp.next) document.write(temp.data + " ");// This code is contributed by todaysgaurav</script> |
Output:
23 11 29 12
Time complexity : O(1)
