private void BuildTree()
{
foreach (KeyValuePair <char, int> symbol in _frequencies)
{
nodes.Add(new HuffmanTreeNode()
{
Symbol = symbol.Key, Frequency = symbol.Value
});
}
while (nodes.Count > 1)
{
List <HuffmanTreeNode> orderedNodes = nodes.OrderBy(node => node.Frequency).ToList();
if (orderedNodes.Count >= 2)
{
HuffmanTreeNode parent = new HuffmanTreeNode()
{
Symbol = '*',
Frequency = orderedNodes[0].Frequency + orderedNodes[1].Frequency,
Left = orderedNodes[0],
Right = orderedNodes[1]
};
nodes.Remove(orderedNodes[0]);
nodes.Remove(orderedNodes[1]);
nodes.Add(parent);
}
Root = nodes.FirstOrDefault();
}
}
public byte[] Decode(byte[] data)
{
HuffmanTreeNode current = Root;
_scratch = new byte[data.Length];
_bitPosition = 0;
int bytePosition = 0;
int lenght = data.Length * 8;
while (_bitPosition < lenght)
{
bool bit = data.ReadBit(_bitPosition, 0);
_bitPosition++;
if (bit)
{
if (current.Right != null)
{
current = current.Right;
}
}
else
{
if (current.Left != null)
{
current = current.Left;
}
}
if (current.IsLeaf())
{
if (current.Symbol == EOD)
{
break;
}
_scratch = _scratch.WriteByte(bytePosition, (byte)current.Symbol);
bytePosition++;
current = Root;
}
}
byte[] decompressedData = new byte[bytePosition];
Array.Copy(_scratch, decompressedData, bytePosition);
_scratch = null;
return(decompressedData);
}