Day 24:HackerRank 30 Days Of Code Solution | More Linked Lists

This post explains the HackerRank 30 Days of Code problem More Linked Lists step by step: the problem statement, input and output format, constraints, a sample test case and a working solution in Java that you can study and run.

Day 24: More Linked Lists

Task

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 a list).

A removeDuplicates function is declared in your editor, which takes a pointer to the head node of a linked list as a parameter. Complete removeDuplicates so that it deletes any duplicate nodes from the list and returns the head of the updated list.

Note: The head pointer may be null, indicating that the list is empty. Be sure to reset your next pointer when performing deletions to avoid breaking the list.

Input Format

You do not need to read any input from stdin. The following input is handled by the locked stub code and passed to the removeDuplicates function:

The first line contains an integer, , the number of nodes to be inserted.

The N subsequent lines each contain an integer describing the dat value of a node being inserted at the list's tail.

Constraints

The data elements of the linked list argument will always be in non-decreasing order.

Output Format

Your removeDuplicates function should return the head of the updated linked list. The locked stub code in your editor will print the returned list to stdout.

Sample Input

6
1
2
2
3
3
4

Sample Output

1 2 3 4

Explanation

N= 6, and our non-decreasing list is {1,2,2,3,3,4} . The values 2 and 3 both occur twice in the list, so we remove the two duplicate nodes. We then return our updated (ascending) list, which is {1,2,3,4}.

More Linked Lists Solution in 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 removeDuplicates(Node head) {
     if(head==null){
         return null;
     }
         Node s=head;
         while(s.next!=null){
             if(s.data==s.next.data){
                 s.next=s.next.next;
             }
             else{
                 s=s.next;
             }
         }
         return head;

     }

    public static  Node insert(Node head,int data)
    {
        Node p=new Node(data);
        if(head==null)
            head=p;
        else if(head.next==null)
            head.next=p;
        else
        {
            Node start=head;
            while(start.next!=null)
                start=start.next;
            start.next=p;

        }
        return head;
    }
    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 T=sc.nextInt();
              while(T-->0){
                  int ele=sc.nextInt();
                  head=insert(head,ele);
              }
              head=removeDuplicates(head);
              display(head);

       }
    }

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Tip: try to solve the problem yourself before reading the solution. Use the code as a reference to check your approach, and make sure you understand why it works.

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