function oddEvenList( head ) {
if (head === null || head.next === null);
let dummyOdd = new ListNode(0);
let dummyEven = new ListNode(0);
let p1 = dummyOdd;
let p2 = dummyEven;
let count = 1;
let curr = head;
while (curr) {
if (count % 2 === 0) {
p2.next = curr;
p2 = p2.next;
} else {
p1.next = curr;
p1 = p1.next;
}
curr = curr.next;
count++;
}
p2.next = null;
p1.next = dummyEven.next;
return dummyOdd.next;
}