// вырезание узла
private HeapNode <TPriority, TItem> MoveToRoot(HeapNode <TPriority, TItem> node)
{
// запомнить родителя
HeapNode <TPriority, TItem> parent = node.Parent;
// удалить родителя, добавить в корневой список, снять пометку
node.RemoveParent();
Trees.AddFirst(node);
node.Marked = false;
return(parent);
}
/// <summary>
/// Cuts the given node from its parent and moves it to the list of root trees. Returns the parent of the node, prior to it
/// being cut
/// </summary>
private HeapNode <TPriority, TItem> MoveToRoot(HeapNode <TPriority, TItem> node)
{
// Remeber ref to parent because child is about to be cut
HeapNode <TPriority, TItem> parent = node.Parent;
// Remove ref to parent and parent ref to child
node.RemoveParent();
Trees.AddFirst(node);
node.Marked = false;
// Return old parent of node
return(parent);
}
// доваить элемент в кучу
public HeapNode <TPriority, TItem> Insert(TPriority priority, TItem value)
{
// добавить дерево с данным элементов
HeapNode <TPriority, TItem> node = new HeapNode <TPriority, TItem>(priority, value);
Trees.AddFirst(node);
//обновить минимум.
// Элемент минимум если он единственный в куче или его приритет меньше приоритета min
if (Count == 0 ||
node.Priority.CompareTo(Minimum.Priority) < 0)
{
minimumTreesNode = Trees.First;
}
Count++;
return(node);
}
/// <summary>
/// Inserts the given item into the heap maintaining the heap order property. O(1) operation
/// </summary>
/// <param name="priority">The priority of the item</param>
/// <param name="value">The object to store</param>
/// <returns>The node that the object is stored in</returns>
public HeapNode <TPriority, TItem> Insert(TPriority priority, TItem value)
{
// Add node as first item in root nodes
HeapNode <TPriority, TItem> node = new HeapNode <TPriority, TItem>(priority, value);
Trees.AddFirst(node);
// Update minimum
if (Count == 0 || // Node is first node inserted? Its minimum
node.Priority.CompareTo(Minimum.Priority) < 0) // Node is less than current minimum? Its minimum
{
minimumTreesNode = Trees.First;
}
Count++;
return(node);
}
/// <summary>
/// Decreases the priority of the given node. O(log n) operation
/// </summary>
/// <param name="node">The node to decrease the value of</param>
/// <param name="priority">The new priority of the node</param>
public void DecreasePriority(HeapNode <TPriority, TItem> node, TPriority priority)
{
// If node priority is already less than given priority
if (node.Priority.CompareTo(priority) < 0)
{
throw new ArgumentException("Priority is not less than current priority");
}
// Decrease key of node
node.Priority = priority;
// If node is a root node, AND its priority is less than the current minimum
if (node.Parent == null &&
priority.CompareTo(Minimum.Priority) < 0)
{
minimumTreesNode = Trees.Find(node); // Set as minimum
}
// Is heap order violated?
if (node.Parent != null &&
node.Priority.CompareTo(node.Parent.Priority) < 0)
{
// Cut from parent and move to root (remember ref to old parent). Node becomes unmarked in the process
HeapNode <TPriority, TItem> parent = MoveToRoot(node);
// Is new priority less than minimum?
if (priority.CompareTo(Minimum.Priority) < 0)
{
minimumTreesNode = Trees.First; // Node is first element in trees list
}
// If parent is unmarked, mark it
if (!parent.Marked)
{
parent.Marked = true;
}
else // Parent IS already marked
{
// Cut parent, move to root, DO FOR ALL ANCESTORS
while (parent != null &&
parent.Marked)
{
parent = MoveToRoot(parent); // Move to root, check its parent
}
}
}
}
// изменить приоритет
public void DecreasePriority(HeapNode <TPriority, TItem> node, TPriority priority)
{
// если св-во кочи сохраняются
if (node.Priority.CompareTo(priority) < 0)
{
throw new ArgumentException();
}
// изменить приоритет
node.Priority = priority;
// если node корневвой узел и его приоритет меньше приритета min - он минимум
if (node.Parent == null &&
priority.CompareTo(Minimum.Priority) < 0)
{
minimumTreesNode = Trees.Find(node);
}
// если порядок кучи нарушен
if (node.Parent != null &&
node.Priority.CompareTo(node.Parent.Priority) < 0)
{
// поместить node в корневой список
HeapNode <TPriority, TItem> parent = MoveToRoot(node);
if (priority.CompareTo(Minimum.Priority) < 0)
{
minimumTreesNode = Trees.First;
}
// отметить родителя если еще не отмечен
if (!parent.Marked)
{
parent.Marked = true;
}
// если уже отмечен то сделать вырезание и для родителей которые уже отмечены
else
{
while (parent != null &&
parent.Marked)
{
parent = MoveToRoot(parent);
}
}
}
}
// удалить дочерний узел
public void RemoveChild(HeapNode <TPriority, TItem> child)
{
Children.Remove(child);
child.Parent = null;
}
// добавить узел как потомок данного узла
public void AddChild(HeapNode <TPriority, TItem> node)
{
Children.Add(node);
node.Parent = this;
}
