Odd Even Linked List

gistfile1.txt

/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} head
 * @return {ListNode}
 */
var oddEvenList = function(head) {
    if (head == null || head.next == null || head.next.next == null) {
        return head;
    }
    let odd = head;
    let evenHead = head.next;
    let even = evenHead;
    while(odd.next!=null && even.next!=null) {
        odd.next = even.next
        odd = odd.next
        even.next = odd.next
        even = even.next
    }
    odd.next = evenHead
    return head
};

//https://leetcode.com/problems/odd-even-linked-list/