1
var partition = function (head, x) {
2
  if (!head) {
3
    return head;
4
  }
5
  const less = [];
6
  const greater = [];
7
  let concat;
8
  rec(head);
9
  return head;
10

11
  function rec(currentNode) {
12
    if (currentNode.val < x) {
13
      less.push(currentNode.val);
14
    } else {
15
      greater.push(currentNode.val);
16
    }
17
    if (!currentNode.next) {
18
      concat = [...less, ...greater];
19
      currentNode.val = concat.pop();
20
      return;
21
    }
22
    rec(currentNode.next);
23
    currentNode.val = concat.pop();
24
  }
25
};