var assert = require('assert');

​

function detectLoop(head) {

  // Fill in this method

  return head;

}

​

class LinkedListNode {

  constructor(val) {

    this.val = val;

    this.next = null;

  }

}

​

const list1 = new LinkedListNode(3);

const nodes = [4, 5, 6, 7, 8, 9, 10];

let head = list1;

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

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

  head.next = newNode;

  head = newNode;

}

list1.next.next.next.next.next.next = list1.next.next;

console.log(detectLoop(list1));

​

function Node(val) {

  this.val = val;