InsertNodeAtSpecificPosLinkedList.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {
  
  // https://www.hackerrank.com/challenges/insert-a-node-at-a-specific-position-in-a-linked-list/problem

    static class SinglyLinkedListNode {
        public int data;
        public SinglyLinkedListNode next;

        public SinglyLinkedListNode(int nodeData) {
            this.data = nodeData;
            this.next = null;
        }
    }

    static 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;
        }
    }

    public static void printSinglyLinkedList(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
        SinglyLinkedListNode previous = null;
        SinglyLinkedListNode next = llist;
        for (int i=0; i<position; i++) {
            previous = next;
            next = next.next;
        }
        SinglyLinkedListNode insertedNode = new SinglyLinkedListNode(data);
        insertedNode.next = next;
        if (previous != null) {
            previous.next = insertedNode;
        }
        return llist;
    }

}

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        SinglyLinkedList llist = new SinglyLinkedList();

        int llistCount = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        for (int i = 0; i < llistCount; i++) {
            int llistItem = scanner.nextInt();
            scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

            llist.insertNode(llistItem);
        }

        int data = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        int position = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

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

        printSinglyLinkedList(llist_head, " ", bufferedWriter);
        bufferedWriter.newLine();

        bufferedWriter.close();

        scanner.close();
    }
}