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

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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 head 
void 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 code 
int 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 node  
class Node: 
    def __init__(self, data): 
        self.data = data 
        self.next = None
  
# Function to remove the first node   
# of the linked list  
def 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 head  
def push(head, data): 
    if not head: 
        return Node(data) 
    temp = Node(data) 
    temp.next = head 
    head = temp 
    return head 
  
# Driver code 
if __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 */

Output:

23 11 29 12

Time complexity : O(1)

GeeksforGeeks has prepared a complete interview preparation course with premium videos, theory, practice problems, TA support and many more features. Please refer Placement 100 for details

My Personal Notes

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

Python3

C#

Recommended Posts: