public void BuildTree(FrequencyDictionary frequencyDictionary)
{
foreach (KeyValuePair <string, int> word in frequencyDictionary.Dictionary)
{
nodes.Add(new NodeHT()
{
Word = word.Key, Frequency = word.Value
});
nodesDictionary.Add(word.Key, nodes.Last());
}
while (nodes.Count > 1)
{
List <NodeHT> orderedNodes = nodes.OrderBy(node => node.Frequency).ToList <NodeHT>();
if (orderedNodes.Count >= 2)
{
// Take first two items
List <NodeHT> taken = orderedNodes.Take(2).ToList();
// Create a parent node by combining the frequencies
NodeHT parent = new NodeHT()
{
Word = "",
Frequency = taken[0].Frequency + taken[1].Frequency,
Left = taken[0],
Right = taken[1]
};
taken[0].Parent = parent;
taken[1].Parent = parent;
nodes.Remove(taken[0]);
nodes.Remove(taken[1]);
nodes.Add(parent);
}
Root = nodes.FirstOrDefault();
Root.Parent = null;
}
}
public List <bool> GetCode(NodeHT nodeLeaf)
{
List <bool> code = new List <bool>();
NodeHT node = nodeLeaf;
NodeHT nodePrev = node;
while (node != Root)
{
node = node.Parent;
if (node?.Right == nodePrev)
{
code.Add(true);
}
if (node?.Left == nodePrev)
{
code.Add(false);
}
nodePrev = node;
}
code?.Reverse();
return(code);
}
public void Decode(BitArray bits, int indexStart, string fileName)
{
StreamWriter fileWrite = new StreamWriter(@fileName);
NodeHT current = this.Root;
string decoded = "";
int endBitArr = bits.Count - 1;
while (bits[endBitArr] != true)
{
endBitArr--;
}
for (int i = indexStart; i < endBitArr; i++)
{
if (bits[i])
{
if (current.Right != null)
{
current = current.Right;
}
}
else
{
if (current.Left != null)
{
current = current.Left;
}
}
if (IsLeaf(current))
{
decoded = current.Word;
fileWrite.Write(decoded);
current = this.Root;
}
}
fileWrite.Close();
}
public bool IsLeaf(NodeHT node)
{
return(node.Left == null && node.Right == null);
}
public HuffmanTree()
{
nodes = new List <NodeHT>();
Root = null;
Frequencies = new FrequencyDictionary();
}