public void DeleteLast()
{
if (Tail != null)
{
if (Tail.Previous != Head)
{
Tail = Tail.Previous;
Tail.Next = null;
}
else
{
Tail = null;
}
}
else
{
Head = null;
}
}
/// <summary>
/// Insert the specified value at the end of the list. Runtime O(1)
/// </summary>
/// <param name="val">Value.</param>
public void Insert(T val)
{
if (Head == null)
{
Head = new DoublyLinkedListNode <T>(val);
}
else
{
var node = new DoublyLinkedListNode <T>(val);
if (Tail == null) //this will only be null if there's one element in the list
{
Tail = node;
Tail.Previous = Head; //set head as prev
Head.Next = Tail;
}
else
{
Tail.Next = node;
node.Previous = Tail; //set old tail as previous to new tail
Tail = node; //set the new tail
}
}
}
public DoublyLinkedList(DoublyLinkedListNode <T> head, DoublyLinkedListNode <T> tail)
{
Head = head;
Tail = tail;
}
/// <summary>
/// Clear the entire list. Runtime O(1)
/// </summary>
public void Clear()
{
Head = null;
Tail = null;
}