老虎-删除排序链表中的重复节点

def delete_duplicate(head):
    h = Node(0)
    k = h
    p = head
    if not p or not p.next:
        return head
    q = p.next
    if p.val!=q.val:
        k.next = p
        k = k.next
    while q.next:
        if q.val!=p.val and q.val!=q.next.val:
            k.next = q
            k = k.next
        p = q
        q = q.next
    if p.val!=q.val:
        k.next = q
        k = k.next
    k.next = None

    return h.next