Good evening! Here's our prompt for today.

Write an algorithm to merge two sorted linked lists and return it as a new sorted list. The new list should be constructed by joining the nodes of the input lists.

You may assume the following node definition:

1public class Node {
2    int value;
3    Node next;
4
5    Node(int value) {
6        this.value = value;
7        this.next = null;
8    }
9
10    public static void main(String[] args) {
11        Node list1 = new Node(1);
12        list1.next = new Node(2);
13
14        System.out.println(list1.value + " -> " + list1.next.value);
15    }
16}

Write a method called mergeSortedLists that would be invoked as such in the following example:

1// List 1: LinkedList<Integer> list1 = new LinkedList<>(Arrays.asList(1,5,6));
2// List 2: LinkedList<Integer> list2 = new LinkedList<>(Arrays.asList(2,3,4));
3
4LinkedList<Integer> mergedList = mergeSortedLists(list1, list2);
5// Output: 1 -> 2 -> 3 -> 4 -> 5 -> 6

As you can see, the linked lists are merged in an ascending sorted order.

Constraints

• Length of the linked lists <= 100000
• The values in the nodes will be in the range -1000000000 and 1000000000
• Expected time complexity : O(n)
• Expected space complexity : O(n) considering the call stack in recursion

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How do I practice this challenge?

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import org.junit.Test;

import org.junit.runner.JUnitCore;

import org.junit.runner.Result;

import org.junit.runner.notification.Failure;

​

import static org.junit.Assert.*;

import org.junit.Before;

​

import java.util.ArrayList;

​

// solution

​

class Solution {

​

    public static LinkedListNode mergeSortedLists(LinkedListNode head1, LinkedListNode head2) {

        // fill in

        // with solution

        return null;

    }

​

    // print your findings using this function!

    public static void log() {

        System.out.println(MainTest.listToString(

            mergeSortedLists(new LinkedListNode(0), new LinkedListNode(1)))

        );

    }

​

}

​

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