private static HuffmanTreeNode CreateAndSortTree(List <HuffmanTreeNode> frequencies)
{
//Sort and create the tree
while (frequencies.Count > 1)
{
// Order frequencies ascending
frequencies = frequencies.OrderBy(n => n.Frequency).ToList();
// Create new tree node with the 2 elements of least frequency
var leastFrequencyNode = new HuffmanTreeNode(frequencies[0].Frequency + frequencies[1].Frequency)
{
Children = frequencies.Take(2).ToArray()
};
// Remove those least frequency elements and append new tree node to frequencies
frequencies = frequencies.Skip(2).Concat(new[] { leastFrequencyNode }).ToList();
// This ultimately results in a tree like structure where the most frequent elements are closer to the root;
// while less frequent elements are farther from the root
// Example:
// (F:4)
// (F:3)
// (F:1)
// (F:2)
// (F:1)
}
return(frequencies.First());
}
private void WriteTreeNode(BitWriter bw, HuffmanTreeNode huffmanTreeNode, int bitCount)
{
if (huffmanTreeNode.IsLeaf)
{
bw.WriteBit(0);
bw.WriteBits(huffmanTreeNode.Code, bitCount);
return;
}
bw.WriteBit(1);
WriteTreeNode(bw, huffmanTreeNode.Children[0], bitCount);
WriteTreeNode(bw, huffmanTreeNode.Children[1], bitCount);
}