void AddToFront(DeqNode node) { if (head == null) { head = new DeqNode(null); tail = new DeqNode(null); head.Next = node; tail.Next = node; } else { if (node.Prev != null) { node.Prev.Next = null; } node.Prev = null; node.Next = head.Next; head.Next.Prev = node; head.Next = node; } if (isbnToPosition.ContainsKey(node.Isbn) == false) { isbnToPosition.Add(node.Isbn, node); } }
void AddToTheFront(string isbn) { var node = new DeqNode(isbn); AddToFront(node); }