LeetCode: Copy List With Random Pointer Solution

1/**
2 * // Definition for a Node.
3 * function Node(val, next, random) {
4 *    this.val = val;
5 *    this.next = next;
6 *    this.random = random;
7 * };
8 */
9
10/**
11 * @param {Node} head
12 * @return {Node}
13 */
14var copyRandomList = function (head) {
15  let newHead
16  let iter
17  let prevIter
18
19  iter = head
20  while (iter) {
21    const node = new Node(iter.val)
22
23    if (prevIter) {
24      prevIter.next = node
25    } else {
26      newHead = node
27    }
28
29    prevIter = node
30    iter.newRef = node
31    iter = iter.next
32  }
33
34  iter = head
35  while (iter) {
36    iter.newRef.random = iter.random?.newRef
37    iter = iter.next
38  }
39
40  return newHead
41}