1
if(!head){
2
        return head;
3
    }
4
    const virsualNode = new ListNode();
5
    virsualNode.next = head;
6
    while(head.next){
7
        let temp = head.next;
8
        head.next = head.next.next;
9
        temp.next = virsualNode.next;
10
        virsualNode.next = temp;
11
    }
12
    return virsualNode.next