/// <summary>
/// Removes and returns the element with highest priority, i.e. lowest key.
/// </summary>
public KeyValuePair <long, T> Dequeue()
{
if (_root == null)
{
throw new InvalidOperationException("priority queue is empty!");
}
PQItem cur = _root;
PQItem parent = null;
while (cur.Children[0] != null)
{
parent = cur;
cur = cur.Children[0];
}
if (parent == null)
{
_root = cur.Children[1];
}
else
{
parent.Children[0] = cur.Children[1];
}
return(new KeyValuePair <long, T>(cur.Key, cur.Value));
}
private void Enqueue(PQItem item, PQItem root)
{
Contract.Requires <ArgumentNullException>(item != null);
Contract.Requires <ArgumentNullException>(root != null);
if (item.Key == root.Key)
{
root.Value = Resolve(root.Value, item.Value);
}
else if (item.Key < root.Key)
{
if (root.Children[0] == null)
{
root.Children[0] = item;
}
else
{
Enqueue(item, root.Children[0]);
}
}
else
{
if (root.Children[1] == null)
{
root.Children[1] = item;
}
else
{
Enqueue(item, root.Children[1]);
}
}
}
/// <summary>
/// Inserts element <paramref name="value"/> for specified <paramref name="key"/>. Lower key means higher priority.
/// </summary>
/// <param name="key">key for which to insert the value</param>
/// <param name="value">element to insert</param>
public void Enqueue(long key, T value)
{
PQItem pqi = new PriorityQueue <T> .PQItem(key, value);
if (_root == null)
{
_root = pqi;
}
else
{
Enqueue(pqi, _root);
}
}
