private static HuffmanTreeNode CombineNextNodes(Queue <HuffmanTreeNode> nodesToProcess, Queue <HuffmanTreeNode> treesToProcess)
{
HuffmanTreeNode node1 = GetNextNode(nodesToProcess, treesToProcess);
HuffmanTreeNode node2 = GetNextNode(nodesToProcess, treesToProcess);
return(new HuffmanTreeNode {
Left = node1,
Right = node2,
TreeWeight = (node1.Weight ?? node1.TreeWeight) + (node2.Weight ?? node2.TreeWeight)
});
}
public static HuffmanTreeNode CalculateHuffmanCodes(List <int> data)
{
Queue <HuffmanTreeNode> nodesToProcess = new Queue <HuffmanTreeNode>();
IOrderedEnumerable <HuffmanTreeNode> nodes = data.Select((weight, index) => new HuffmanTreeNode
{
Id = index,
Weight = weight
}).OrderBy(n => n.Weight);
foreach (HuffmanTreeNode node in nodes)
{
nodesToProcess.Enqueue(node);
}
Queue <HuffmanTreeNode> treesToProcess = new Queue <HuffmanTreeNode>();
while (nodesToProcess.Count > 0 || treesToProcess.Count > 1)
{
HuffmanTreeNode combinedNode = CombineNextNodes(nodesToProcess, treesToProcess);
treesToProcess.Enqueue(combinedNode);
}
return(treesToProcess.Dequeue());
}
private static int DepthEvaluator(HuffmanTreeNode tree, Func <int, int, int> tiebreaker)
{
if (tree == null)
{
return(0);
}
if (tree.Left == null && tree.Right == null)
{
return(1);
}
if (tree.Left == null)
{
return(DepthEvaluator(tree.Right, tiebreaker) + 1);
}
if (tree.Right == null)
{
return(DepthEvaluator(tree.Left, tiebreaker) + 1);
}
return(tiebreaker(DepthEvaluator(tree.Right, tiebreaker), DepthEvaluator(tree.Left, tiebreaker)) + 1);
}
private static int MaxDepth(HuffmanTreeNode tree)
{
return(DepthEvaluator(tree, Math.Max));
}
public static (int, int) GetTreeDepths(HuffmanTreeNode tree)
{
return(MinDepth(tree), MaxDepth(tree));
}