Good afternoon! Here's our prompt for today.

Given a linked list, can you write a method to get a random node within it? Let's assume you're given a random node generator. The linked list will have at least 2 nodes, and may look something like this:

1 -> 2 -> 3 -> 4

The odds of getting any number between 1 and 4 inclusive should be the exactly the same.

You have access to this definition of a Linked List node:

1function Node(val) {
2  this.val = val;
3  this.next = null;
4}

Constraints

• Length of the linked list <= 10000
• The nodes will always contain integer values between -1000000000 and 1000000000
• Expected time complexity : O(n)
• Expected space complexity : O(n)

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

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    'PASSED: ' + 'Checking that we grab a random list node  for `list1`'

var assert = require('assert');

​

function fetchRandomNode(headNode) {

  // grab random node

  return headNode;

}

​

function Node(val) {

  this.val = val;

  this.next = null;

}

​

function LinkedListNode(val) {

  this.val = val;

  this.next = null;

}

​

var list1 = new LinkedListNode(3);

var nodes1 = [4, 5, 6, 7, 8, 9, 10];

createNodes(list1, nodes1);

​

var list2 = new LinkedListNode(1);

var nodes2 = [2, 3, 4, 5, 6, 7, 8];

createNodes(list2, nodes2);

​

function createNodes(head, nodes) {

  for (let i = 0; i < nodes.length; i++) {

    var newNode = new LinkedListNode(nodes[i]);

    head.next = newNode;

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