public void RemoveLast()
{
if (IsEmpty)
{
throw new InvalidOperationException();
}
if (Count == 1)
{
Head = null;
Tail = null;
}
else
{
Tail.Previous.Next = null; //null the last node;
Tail = Tail.Previous; //shift the tail (now it's the former penultimate node);
}
Count--;
}
public void RemoveFirst()
{
if (IsEmpty)
{
throw new InvalidOperationException();
}
//shift head;
Head = Head.Next;
Count--;
if (IsEmpty)
{
Tail = null;
}
else
{
Head.Previous = null;
}
}