/// <summary>
/// Uses Equality check only for removing from the queue.
/// Might cost O(n) if all items are in the queue and not the heap.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
public bool Remove
(
IBinaryHeapItem item
)
{
if (item.GetIndexInHeap() == BinaryHeap.REMOVED_FROM_HEAP) // Or from queue.
{
return(false);
}
bool removedFromQueue = false;
// Remove from the queue if it's there, keeping the order in the queue.
for (int i = 0; i < this.queue.Count; ++i)
{
IBinaryHeapItem temp = this.queue.Dequeue();
if (temp.Equals(item))
{
removedFromQueue = true;
temp.SetIndexInHeap(BinaryHeap.REMOVED_FROM_HEAP);
}
else
{
this.queue.Enqueue(temp);
}
}
if (removedFromQueue == true)
{
return(true);
}
return(this.heap.Remove(item));
}
/// <summary>
/// Removes an item from the binary heap.
/// Assumes item is or was in the heap. Doesn't use Equality checks.
/// This will not remove duplicates.
/// </summary>
/// <param name="item">The item to be removed.</param>
/// <returns>Boolean true if the item was removed.</returns>
public bool Remove(IBinaryHeapItem item)
{
if (item == null)
{
return(false);
}
int child_index = item.GetIndexInHeap();
if (child_index == REMOVED_FROM_HEAP)
{
return(false);
}
_data[child_index].SetIndexInHeap(REMOVED_FROM_HEAP);
if (child_index == 0) // This seems unnecessary
{
Remove();
return(true);
}
IBinaryHeapItem to_remove = _data[child_index];
// Bubble to_remove up the heap
// If UpHeap received an index parameter instead of always starting from the last element,
// we could maybe remove some code duplication.
int father_index = Parent(child_index);
while (child_index != 0)
{
_data[child_index] = _data[father_index]; // Swap parent down
_data[child_index].SetIndexInHeap(child_index);
child_index = father_index;
father_index = Parent(child_index);
}
//we got to 0
_data[0] = to_remove;
Remove(); // Ignoring the returned value.
return(true);
}
/// <summary>
/// Assumes item was added to the open list in the past
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
public bool Contains(IBinaryHeapItem item)
{
return(item.GetIndexInHeap() != BinaryHeap.REMOVED_FROM_HEAP);
}