private void SiftDown(int index)
{
PriorityQueueNodeWrapper min = minHeap[index];
int minIndex = index;
int leftChildIndex = GetLeftChildIndex(index);
if (leftChildIndex < Count() && ComparePriorities(minHeap[leftChildIndex], min) < 0)
{
min = minHeap[leftChildIndex];
minIndex = leftChildIndex;
}
int rightChildIndex = GetRightChildIndex(index);
if (rightChildIndex < Count() && ComparePriorities(minHeap[rightChildIndex], min) < 0)
{
minIndex = rightChildIndex;
}
if (minIndex != index)
{
SwapAndUpdateMap(index, minIndex);
SiftDown(minIndex);
}
}
private void AttachNodeAtIndex(PriorityQueueNodeWrapper wrapper, int index)
{
GrowHeapByOne();
this.minHeap[index] = wrapper;
this.nodeUniqueKeyToHeapIndexMap[wrapper.Data.UniqueKey] = index;
}
public void Enqueue(PriorityQueueNode node)
{
int lastIndex = Count();
PriorityQueueNodeWrapper wrapper = new PriorityQueueNodeWrapper(node);
AttachNodeAtIndex(wrapper, lastIndex);
SiftUp(lastIndex);
}
private PriorityQueueNodeWrapper DetachNodeAtIndex(int index)
{
PriorityQueueNodeWrapper wrapper = minHeap[index];
this.nodeUniqueKeyToHeapIndexMap.Remove(wrapper.Data.UniqueKey);
ShrinkHeapByOne();
return(wrapper);
}
private int ComparePriorities(PriorityQueueNodeWrapper node1, PriorityQueueNodeWrapper node2)
{
int result = node1.Priority.CompareTo(node2.Priority);
if (result == 0)
{
result = node1.Sequence.CompareTo(node2.Sequence);
}
return(result);
}
public override string ToString()
{
StringBuilder sb = new StringBuilder();
for (int i = 0; i < heapCount; i++)
{
PriorityQueueNodeWrapper wrapper = minHeap[i];
sb.AppendLine(string.Format("HeapIndex: {0} UniqueKey: {1} Priority: {2} Sequence: {3}",
i, wrapper.Data.UniqueKey, wrapper.Priority, wrapper.Sequence));
}
return(sb.ToString());
}
public PriorityQueueNode Dequeue()
{
if (minHeap.Count == 0)
{
throw new PriorityQueueEmptyException();
}
int topIndex = 0;
PriorityQueueNodeWrapper min = DetachNodeAtIndex(topIndex);
int lastIndex = Count();
PriorityQueueNodeWrapper last = DetachNodeAtIndex(lastIndex);
AttachNodeAtIndex(last, topIndex);
SiftDown(0);
return(min);
}