public HuffTreeNode(double inFreq, HuffTreeNode inLeftChild, HuffTreeNode inRightChild) //Constructor used when combining nodes.
{
freq = inFreq;
leftChild = inLeftChild;
rightChild = inRightChild;
parent = null;
}
public HuffTreeNode(double inFreq) //Used when constructing from HuffLeafNode.
{
freq = inFreq;
leftChild = null;
rightChild = null;
parent = null;
}
//Build the Huffman tree.
private void buildHuff(List <SymbolFreq> freqTbl, List <HuffLeafNode> leafNodePtrs)
{
List <HuffTreeNode> huffTree = new List <HuffTreeNode>(); //Contains the nodes that will be combined into the Hoffman tree.
HuffTreeNode min1, min2, newNode;
HuffLeafNode tempNode;
foreach (SymbolFreq SF in freqTbl) //Load the two Lists with leaf nodes.
{
tempNode = new HuffLeafNode(SF.getFreq(), SF.getSymbol());
huffTree.Add(tempNode);
leafNodePtrs.Add(tempNode);
}
while (huffTree.Count > 1) //Combine nodes until only root node left.
{
min1 = huffTree[0];
min2 = huffTree[1];
if (huffTree.Count != 2) //if only 2 nodes left, proceed to combine stage.
{
for (int i = 2; i < huffTree.Count; i++) //Determine smallest in two elements array.
{
if ((huffTree[i].getFreq() < min1.getFreq()) && (huffTree[i].getFreq() < min2.getFreq())) //Current node frequency smaller than both min1 & min2.
{
if (min1.getFreq() <= min2.getFreq()) //Find smallest of min1 & min2. If they are equal, replace min1.
{
min1 = huffTree[i];
}
else
{
min2 = huffTree[i];
}
}
else if (huffTree[i].getFreq() < min1.getFreq()) //if current node frequency smaller than min1 then set current node as min1.
{
min1 = huffTree[i];
}
else if (huffTree[i].getFreq() < min2.getFreq()) //if current node frequency smaller than min2 then set current node as min2.
{
min2 = huffTree[i];
}
}
}
newNode = new HuffTreeNode(min1.getFreq() + min2.getFreq(), min1, min2); //create new non-symbol node and update the Huffman tree.
min1.setParent(newNode); //Update parent references.
min2.setParent(newNode);
huffTree.Add(newNode); //Add new node to tree.
huffTree.Remove(min1); //Remove combines nodes from tree.
huffTree.Remove(min2);
}
calcHuffCode(leafNodePtrs); //Calculate the huffman code for each leaf node.
}
public void setParent(HuffTreeNode inParent)
{
parent = inParent;
}
