Day 15: Linked List | 30 Days Of Code | HackerRank Solution

Hello coders, today we are going to solve Day 15:Linked List HackerRank Solution in C++, Java and Python.

Objective

Today we will work with a Linked List. 

A Node class is provided for you in the editor. A Node object has an integer data field, data, and a Node instance pointer, next, pointing to another node (i.e.: the next node in the list).

A Node insert function is also declared in your editor. It has two parameters: a pointer, head, pointing to the first node of a linked list, and an integer, data, that must be added to the end of the list as a new Node object.

Task

Complete the insert function in your editor so that it creates a new Node (pass data as the Node constructor argument) and inserts it at the tail of the linked list referenced by the head parameter. Once the new node is added, return the reference to the head node.

Note: The head argument is null for an empty list.

Input Format

The first line contains T, the number of elements to insert.
Each of the next T lines contains an integer to insert at the end of the list.

Output Format

Return a reference to the head node of the linked list.

Sample Input

STDIN   Function
-----   --------
4       T = 4
2       first data = 2
3
4
1       fourth data = 1

Sample Output

2 3 4 1

Explanation

T = 4, so your method will insert 4 nodes into an initially empty list.
First the code returns a new node that contains the data value 2 as the head of the list. Then create and insert nodes 3, 4, and 1 at the tail of the list.

Solution – Day 15: Linked List

C++

#include <iostream>
#include <cstddef>
using namespace std;	
class Node
{
    public:
        int data;
        Node *next;
        Node(int d){
            data=d;
            next=NULL;
        }
};
class Solution{
    public:
      Node* insert(Node * const head,const int data)
      {
          Node * newNode = new Node(data);
          Node * tail = head;
          if ( !head ) { return newNode; }
          
          // Locate tail node
          for (;tail->next; tail = tail->next);

          // Insert at end of list
          tail->next = newNode;
          
          return head;
      }
      void display(Node *head)
      {
          Node *start=head;
          while(start)
          {
              cout<<start->data<<" ";
              start=start->next;
          }
      }
};
int main()
{
	Node* head=NULL;
  	Solution mylist;
    int T,data;
    cin>>T;
    while(T-->0){
        cin>>data;
        head=mylist.insert(head,data);
    }	
	mylist.display(head);
		
}

Java

import java.io.*;
import java.util.*;
class Node {
    int data;
    Node next;
    Node(int d) {
        data = d;
        next = null;
    }
}

class Solution {
    public static  Node insert(Node head,int data) {
        if(head==null){
            return new Node (data);
        }
        else if(head.next==null){
            head.next=new Node (data);
        }
        else{
            insert(head.next,data);

        }
        return head;
    

        //Complete this method
    }

    public static void display(Node head) {
        Node start = head;
        while(start != null) {
            System.out.print(start.data + " ");
            start = start.next;
        }
    }

    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        Node head = null;
        int N = sc.nextInt();

        while(N-- > 0) {
            int ele = sc.nextInt();
            head = insert(head,ele);
        }
        display(head);
        sc.close();
    }
}

Python

class Node:
    def __init__(self,data):
        self.data = data
        self.next = None 
class Solution: 
    def display(self,head):
        current = head
        while current:
            print(current.data,end=' ')
            current = current.next
    def insert(self, head, data):
        if head is None:
            head = Node(data)
        else:
            curr = head
            while curr.next:
                curr = curr.next
            curr.next = Node(data)
        return head
mylist= Solution()
T=int(input())
head=None
for i in range(T):
    data=int(input())
    head=mylist.insert(head,data)    
mylist.display(head); 	  

Disclaimer: The above Problem (Day 15: Linked List) is generated by Hacker Rank but the Solution is Provided by CodingBroz. This tutorial is only for Educational and Learning Purpose.