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  1. Prepare
  2. Data Structures
  3. Linked Lists
  4. Insert a node at the head of a linked list
  5. Discussions

Insert a node at the head of a linked list

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  • alban_tyrex
     + 0 comments

    Here is my c++ solution you watch vide explanation here : https://youtu.be/COnfpdhOlN8

    SinglyLinkedListNode* insertNodeAtHead(SinglyLinkedListNode* llist, int data) {
   SinglyLinkedListNode* new_node = new SinglyLinkedListNode(data);
   new_node -> next = llist;
   return new_node;
}

  • vknakul43
     + 0 comments

    Simple Solution

    C++

    #include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

class Node {
    public:
    int data;
    Node* next;
    
    Node(int data) {
        this->data = data;
        this->next = NULL;
    }
};

class LinkedList {
    public:
    Node* head;
    
    LinkedList() {
        head = NULL;
    }
    
    void insertHead(int val) {
        Node * node = new Node(val);
        node->next = head;
        head = node;
    }
};

int main() {
    int val, n;
    cin >> n;
    LinkedList l = LinkedList(); 
    for (int i = 0; i < n; i++) {
        cin >> val;
        l.insertHead(val);
    } 
    
    Node* current = l.head;
    while(current) {
        cout << current->data << endl;
        current = current->next;
    }
    
    return 0;
}

    Java

    import java.io.*;
import java.util.*;

class Node {
    int data;
    Node next;
    
    public Node(int data) {
        this.data = data;
    }
}

class LinkedList {
    Node head;
    
    public LinkedList() {
        this.head = null;
    }
    
    public void insertHead(int val) {
        Node node = new Node(val);
        node.next = head;
        head = node;
    }
}

public class Solution {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        LinkedList l = new LinkedList();
        
        for (int i = 0; i < n; i++) {
            int val = sc.nextInt();
            l.insertHead(val);
        }
        
        Node current = l.head;
        while(current != null) {
            System.out.println(current.data);
            current = current.next;
        }
    }
}

  • dsv3328
     + 0 comments

    def insertNodeAtHead(llist, data): newnode = SinglyLinkedListNode(data) newnode.next = llist return newnode

  • techiesathya
     + 0 comments

    It looks like there is a problem with the c# solution. I am getting compilation error in the pre-writtern class

  • slava_kozlov
     + 0 comments

    The given C# classes do not compile. This needs to be fixed.