public void Enqueue(PriorityQueueNode <TData> node, int priority)
{
if (_currentIndex >= nodes.Length)
{
throw new InvalidOperationException("The heap has reached its maximum capacity. Cannot enqueue further nodes.");
}
if (priority < 0)
{
throw new ArgumentOutOfRangeException("Priority cannot be less than 0!");
}
// Place the new element in the next available position in the array
node.index = _currentIndex;
node.priority = priority;
nodes[_currentIndex] = node;
// Compare the new element with its parent - if smaller, then swap with parent
PriorityQueueNode <TData> parent;
while ((parent = GetParent(node)) != null && parent.priority > node.priority)
{
Swap(node, parent);
}
_currentIndex++;
_nodeCount++;
}
public PriorityQueueNode <TData> GetParent(PriorityQueueNode <TData> node)
{
if (node.index < 2)
{
return(null);
}
return(nodes[node.index / 2]);
}
public void Swap(PriorityQueueNode <TData> first, PriorityQueueNode <TData> second)
{
int temp = first.index;
first.index = second.index;
second.index = temp;
nodes[first.index] = first;
nodes[second.index] = second;
}
public PriorityQueueNode <TData> GetRight(PriorityQueueNode <TData> node)
{
int index = 2 * node.index + 1;
if (index >= maxNodes)
{
return(null);
}
return(nodes[index]);
}
public PriorityQueueNode <TData> Dequeue()
{
if (IsEmpty())
{
return(null);
}
PriorityQueueNode <TData> dequeuedNode = nodes[1];
PriorityQueueNode <TData> swapperNode = nodes[_currentIndex - 1];
nodes[1] = swapperNode;
nodes[_currentIndex - 1] = null;
swapperNode.index = 1;
PriorityQueueNode <TData> left = GetLeft(swapperNode);
PriorityQueueNode <TData> right = GetRight(swapperNode);
while ((left != null && swapperNode.priority > left.priority) || (right != null && swapperNode.priority > right.priority))
{
if (left == null)
{
Swap(swapperNode, right);
}
else if (right == null)
{
Swap(swapperNode, left);
}
else
{
if (left.priority <= right.priority)
{
Swap(swapperNode, left);
}
else
{
Swap(swapperNode, right);
}
}
left = GetLeft(swapperNode);
right = GetRight(swapperNode);
}
_currentIndex--;
_nodeCount--;
return(dequeuedNode);
}
public void Remove(PriorityQueueNode <TData> node)
{
if (nodes[node.index] != node)
{
throw new InvalidOperationException("The node being removed has already been removed (index mismatch).");
}
PriorityQueueNode <TData> swapperNode = nodes[_currentIndex - 1];
nodes[node.index] = swapperNode;
nodes[_currentIndex - 1] = null;
swapperNode.index = node.index;
PriorityQueueNode <TData> left = GetLeft(swapperNode);
PriorityQueueNode <TData> right = GetRight(swapperNode);
while ((left != null && swapperNode.priority > left.priority) || (right != null && swapperNode.priority > right.priority))
{
if (left == null)
{
Swap(swapperNode, right);
}
else if (right == null)
{
Swap(swapperNode, left);
}
else
{
if (left.priority <= right.priority)
{
Swap(swapperNode, left);
}
else
{
Swap(swapperNode, right);
}
}
left = GetLeft(swapperNode);
right = GetRight(swapperNode);
}
_currentIndex--;
_nodeCount--;
}
public bool Contains(PriorityQueueNode <TData> node)
{
if (nodes[node.index] == node)
{
return(true);
}
else
{
for (int i = 0; i < _currentIndex; i++)
{
if (nodes[i] == node)
{
return(true);
}
}
}
return(false);
}
public void UpdatePriority(PriorityQueueNode <TData> node, int priority)
{
Remove(node);
Enqueue(node, priority);
}
