Insert A Node at Specific position in linkedList Problem HackerRank

 Given the pointer to the head node of a linked list and an integer to insert at a certain position, create a new node with the given integer as its  attribute, insert this node at the desired position and return the head node.

A position of 0 indicates head, a position of 1 indicates one node away from the head and so on. The head pointer given may be null meaning that the initial list is empty.

Example

 refers to the first node in the list 

Insert a node at position  with . The new list is 

Function Description Complete the function insertNodeAtPosition in the editor below. It must return a reference to the head node of your finished list.

insertNodeAtPosition has the following parameters:

head: a SinglyLinkedListNode pointer to the head of the list

data: an integer value to insert as data in your new node

position: an integer position to insert the new node, zero based indexing

Returns

SinglyLinkedListNode pointer: a reference to the head of the revised list

Input Format

The first line contains an integer , the number of elements in the linked list.

Each of the next  lines contains an integer SinglyLinkedListNode[i].data.

The next line contains an integer , the data of the node that is to be inserted.

The last line contains an integer .

Constraints

, where  is the  element of the linked list.

.

Sample Input

3

16

13

7

1

2

Sample Output

16 13 1 7

Explanation

The initial linked list is . Insert  at the position  which currently has  in it. The updated linked list is .

import java.io.*;

import java.math.*;

import java.security.*;

import java.text.*;

import java.util.*;

import java.util.concurrent.*;

import java.util.function.*;

import java.util.regex.*;

import java.util.stream.*;

import static java.util.stream.Collectors.joining;

import static java.util.stream.Collectors.toList;

class SinglyLinkedListNode {

    public int data;

    public SinglyLinkedListNode next;

    public SinglyLinkedListNode(int nodeData) {

        this.data = nodeData;

        this.next = null;

    }

}

class SinglyLinkedList {

    public SinglyLinkedListNode head;

    public SinglyLinkedListNode tail;

    public SinglyLinkedList() {

        this.head = null;

        this.tail = null;

    }

    public void insertNode(int nodeData) {

        SinglyLinkedListNode node = new SinglyLinkedListNode(nodeData);

        if (this.head == null) {

            this.head = node;

        } else {

            this.tail.next = node;

        }

        this.tail = node;

    }

}

class SinglyLinkedListPrintHelper {

    public static void printList(SinglyLinkedListNode node, String sep, BufferedWriter bufferedWriter) throws IOException {

        while (node != null) {

            bufferedWriter.write(String.valueOf(node.data));

            node = node.next;

            if (node != null) {

                bufferedWriter.write(sep);

            }

        }

    }

}

class Result {

    /*

     * Complete the 'insertNodeAtPosition' function below.

     *

     * The function is expected to return an INTEGER_SINGLY_LINKED_LIST.

     * The function accepts following parameters:

     *  1. INTEGER_SINGLY_LINKED_LIST llist

     *  2. INTEGER data

     *  3. INTEGER position

     */

    /*

     * For your reference:

     *

     * SinglyLinkedListNode {

     *     int data;

     *     SinglyLinkedListNode next;

     * }

     *

     */

    public static SinglyLinkedListNode insertNodeAtPosition(SinglyLinkedListNode llist, int data, int position) {

    // Write your code here

        // Create the new node

        SinglyLinkedListNode newNode = new SinglyLinkedListNode(data);

        // If inserting at the head (position 0)

        if (position == 0) {

            newNode.next = llist;

            return newNode; // New head of the list

        }

        // Traverse to the node before the insertion point

        SinglyLinkedListNode temp = llist;

        for (int i = 0; temp != null && i < position - 1; i++) {

            temp = temp.next;

        }

        // If position is out of bounds

        if (temp == null) {

            System.out.println("Position out of range");

            return llist;

        }

        // Insert the new node

        newNode.next = temp.next;

        temp.next = newNode;

        return llist; // Return the original head

    }

}

public class Solution {

    public static void main(String[] args) throws IOException {

        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        SinglyLinkedList llist = new SinglyLinkedList();

        int llistCount = Integer.parseInt(bufferedReader.readLine().trim());

        IntStream.range(0, llistCount).forEach(i -> {

            try {

                int llistItem = Integer.parseInt(bufferedReader.readLine().trim());

                llist.insertNode(llistItem);

            } catch (IOException ex) {

                throw new RuntimeException(ex);

            }

        });

        int data = Integer.parseInt(bufferedReader.readLine().trim());

        int position = Integer.parseInt(bufferedReader.readLine().trim());

        SinglyLinkedListNode llist_head = Result.insertNodeAtPosition(llist.head, data, position);

        SinglyLinkedListPrintHelper.printList(llist_head, " ", bufferedWriter);

        bufferedWriter.newLine();

        bufferedReader.close();

        bufferedWriter.close();

    }

}