/** Deletes an item from the rear of Deque. Return true if the operation is successful. */
public bool DeleteLast()
{
if (CurrentLength <= 0)
{
return(false);
}
else
{
if (StartCircularDeque.Next == null)
{
if (StartCircularDeque.Previous == null)
{
StartCircularDeque = null;
}
else
{
CircularDeque PreviousCircularDeque = StartCircularDeque.Previous;
StartCircularDeque.Val = PreviousCircularDeque.Val;
StartCircularDeque.Previous = PreviousCircularDeque.Previous;
}
}
else
{
CircularDeque _CircularDeque = StartCircularDeque;
while (_CircularDeque.Next != null)
{
_CircularDeque = _CircularDeque.Next;
}
if (_CircularDeque.Previous != null)//队列中元素超过2个
{
CircularDeque PreviousCircularDeque = _CircularDeque.Previous;
PreviousCircularDeque.Next = null;
}
else//队列中元素不足2个
{
StartCircularDeque = null;
CurrentLength = 0;
}
}
if (CurrentLength >= 1)
{
CurrentLength--;
}
return(true);
}
}
/** Get the last item from the deque. */
public int GetRear()
{
if (CurrentLength <= 0)
{
return(-1);
}
else
{
CircularDeque _CircularDeque = StartCircularDeque;
while (_CircularDeque.Next != null)
{
_CircularDeque = _CircularDeque.Next;
}
return(_CircularDeque.Val);
}
}
/** Get the front item from the deque. */
public int GetFront()
{
if (CurrentLength <= 0)
{
return(-1);
}
else
{
CircularDeque _CircularDeque = StartCircularDeque;
while (_CircularDeque.Previous != null)
{
_CircularDeque = _CircularDeque.Previous;
}
return(_CircularDeque.Val);
}
}
/** Adds an item at the rear of Deque. Return true if the operation is successful. */
public bool InsertLast(int value)
{
if (CurrentLength >= Length)
{
return(false);
}
else
{
if (StartCircularDeque == null)
{
StartCircularDeque = new CircularDeque();
StartCircularDeque.Previous = null;
StartCircularDeque.Val = value;
StartCircularDeque.Next = null;
}
else
{
CircularDeque _CircularDeque = StartCircularDeque;
while (_CircularDeque.Next != null)
{
_CircularDeque = _CircularDeque.Next;
}
CircularDeque LastCircularDeque = new CircularDeque();
LastCircularDeque.Val = value;
LastCircularDeque.Previous = _CircularDeque;
LastCircularDeque.Next = null;
_CircularDeque.Next = LastCircularDeque;
}
if (CurrentLength < Length)
{
CurrentLength++;
}
return(true);
}
}
