public void AddLast(T value)
{
MyLinkedListNode <T> node = new MyLinkedListNode <T>(value);
if (Count == 0)
{
_head = node;
}
else
{
_tail.Next = node;
// До: Head -> 3 5 -> null
// После:Head -> 3 5 7 -> null
// 7.Previous = 5
node.Previous = _tail;
}
_tail = node;
count++;
}
public void RemoveLast()
{
if (Count != 0)
{
if (Count == 1)
{
_head = null;
_tail = null;
}
else
{
// До: Head --> 3 --> 5 --> 7
// Tail = 7
// После: Head --> 3 --> 5 --> null
// Tail = 5
// Обнуляем 5.Next
_tail.Previous.Next = null;
_tail = _tail.Previous;
}
count--;
}
}
public void RemoveFirst()
{
if (Count != 0)
{
// До: Head -> 3 5
// После: Head -------> 5
// Head -> 3 -> null
// Head ------> null
_head = _head.Next;
count--;
if (Count == 0)
{
_tail = null;
}
else
{
// 5.Previous было 3; теперь null.
_head.Previous = null;
}
}
}