/// <summary>
/// If the queue is empty we do just return null
///
/// Operation: O(log n)
/// </summary>
public T Dequeue()
{
if (IsEmpty())
{
return(default(T));
}
KeyValueEntry <int, T> result = _queue[0];
_queue[0] = _queue[Count - 1];
RemovePosition(result.Value);
UpdatePosition(_queue[0].Value, 0);
_queue[Count - 1] = null;
Count--;
BubbleDown(0);
return(result.Value);
}
/// <summary>
/// Operation: O(log n)
///
/// InvalidOperationException: If we add an element which is alread in the Queue
/// </summary>
public void Enqueue(T element, int priority)
{
if (Contains(element))
{
throw new InvalidOperationException("Cannot add an element which is already in the queue");
}
if (Count == _queue.Length)
{
KeyValueEntry <int, T>[] oldQueue = _queue;
_queue = new KeyValueEntry <int, T> [oldQueue.Length * 3 / 2 + 1];
Array.Copy(oldQueue, _queue, oldQueue.Length);
}
_queue[Count] = new KeyValueEntry <int, T>(priority, element);
UpdatePosition(element, Count);
Count++;
BubbleUp(Count - 1);
}