insert-a-node-at-a-specific-position-in-a-linked-list.java

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) {
        SinglyLinkedListNode root = llist;
        for (int x = 0; x < position - 1; x++) {
            if (llist.next == null) {
                break;
            }
            llist = llist.next;
        }

        SinglyLinkedListNode tmp = new SinglyLinkedListNode(data);
        tmp.next = llist.next;
        llist.next = tmp;

        return root;
    }

}

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();
    }
}