/// <summary>
/// Update the Heap with new value for this node pointer
/// O(1) complexity amortized
/// </summary>
/// <param name="key"></param>
public void DecrementKey(FibornacciHeapNode <T> node)
{
if (node.Parent == null &&
minNode.Value.CompareTo(node.Value) > 0)
{
minNode = node;
}
var current = node;
if (current.Parent != null &&
current.Value.CompareTo(current.Parent.Value) < 0)
{
var parent = current.Parent;
//if parent already lost one child
//then cut current and parent
if (parent.LostChild)
{
parent.LostChild = false;
var grandParent = parent.Parent;
//mark grand parent
if (grandParent != null)
{
Cut(parent);
Cut(current);
}
}
else
{
Cut(current);
}
}
}
/// <summary>
/// Merge roots with same degrees in Forest
/// </summary>
private void Meld()
{
if (heapForestHead == null)
{
maxNode = null;
return;
}
//degree - node dictionary
var mergeDictionary = new Dictionary <int, FibornacciHeapNode <T> >();
var current = heapForestHead;
maxNode = current;
while (current != null)
{
current.Parent = null;
var next = current.Next;
//no same degree already in merge dictionary
//add to hash table
if (!mergeDictionary.ContainsKey(current.Degree))
{
mergeDictionary.Add(current.Degree, current);
if (maxNode == current)
{
maxNode = null;
}
DeleteNode(ref heapForestHead, current);
current = next;
continue;
}
//insert back to forest by merging current tree
//with existing tree in merge dictionary
else
{
var currentDegree = current.Degree;
var existing = mergeDictionary[currentDegree];
if (existing.Value.CompareTo(current.Value) > 0)
{
current.Parent = existing;
DeleteNode(ref heapForestHead, current);
var childHead = existing.ChildrenHead;
InsertNode(ref childHead, current);
existing.ChildrenHead = childHead;
existing.Degree++;
InsertNode(ref heapForestHead, existing);
current = existing;
current.Next = next;
}
else
{
existing.Parent = current;
var childHead = current.ChildrenHead;
InsertNode(ref childHead, existing);
current.ChildrenHead = childHead;
current.Degree++;
}
if (maxNode == null ||
maxNode.Value.CompareTo(current.Value) < 0)
{
maxNode = current;
}
mergeDictionary.Remove(currentDegree);
}
}
//insert back trees with unique degrees to forest
if (mergeDictionary.Count > 0)
{
foreach (var node in mergeDictionary)
{
InsertNode(ref heapForestHead, node.Value);
if (maxNode == null ||
maxNode.Value.CompareTo(node.Value.Value) < 0)
{
maxNode = node.Value;
}
}
mergeDictionary.Clear();
}
}
private void Meld()
{
if (heapForestHead == null)
{
minNode = null;
return;
}
var mergeDictionary = new Dictionary <int, FibornacciHeapNode <T> >();
var current = heapForestHead;
minNode = current;
while (current != null)
{
current.Parent = null;
var next = current.Next;
if (!mergeDictionary.ContainsKey(current.Degree))
{
mergeDictionary.Add(current.Degree, current);
if (minNode == current)
{
minNode = null;
}
DeleteNode(ref heapForestHead, current);
current = next;
continue;
}
else
{
var currentDegree = current.Degree;
var existing = mergeDictionary[currentDegree];
if (existing.Value.CompareTo(current.Value) < 0)
{
current.Parent = existing;
DeleteNode(ref heapForestHead, current);
var childHead = existing.ChildrenHead;
InsertNode(ref childHead, current);
existing.ChildrenHead = childHead;
existing.Degree++;
InsertNode(ref heapForestHead, existing);
current = existing;
current.Next = next;
}
else
{
existing.Parent = current;
var childHead = current.ChildrenHead;
InsertNode(ref childHead, existing);
current.ChildrenHead = childHead;
current.Degree++;
}
if (minNode == null ||
minNode.Value.CompareTo(current.Value) > 0)
{
minNode = current;
}
mergeDictionary.Remove(currentDegree);
}
}
if (mergeDictionary.Count > 0)
{
foreach (var node in mergeDictionary)
{
InsertNode(ref heapForestHead, node.Value);
if (minNode == null ||
minNode.Value.CompareTo(node.Value.Value) > 0)
{
minNode = node.Value;
}
}
mergeDictionary.Clear();
}
}
