public void combineTrees(RootedBinaryTree <T> leftTree, RootedBinaryTree <T> rightTree)
{
root.leftChild = leftTree.root;
root.rightChild = rightTree.root;
leftTree.root.parent = root;
rightTree.root.parent = root;
root.parent = null;
leftTree.currentPosition = root;
rightTree.currentPosition = root;
}
} //end decompress()
private static void huffman(Word[] theWords)
{
List <RootedBinaryTree <Word> > treeArray = new List <RootedBinaryTree <Word> >();
//make our initial list of binary trees
for (int i = 0; i < theWords.Length; i++)
{
treeArray.Add(new RootedBinaryTree <Word>(theWords[i]));
}
//combine trees
while (treeArray.Count > 1)
{
Word newWord = new Word();
newWord.plainWord = null;
newWord.codeWord = null;
//combine the probabilities
newWord.probability = treeArray.ElementAt(0).getData().probability + treeArray.ElementAt(1).getData().probability;
//make a new tree for the combined trees.
RootedBinaryTree <Word> combinedTrees = new RootedBinaryTree <Word>(newWord);
combinedTrees.combineTrees(treeArray.ElementAt(0), treeArray.ElementAt(1));
//make sure we are at root
combinedTrees.toRoot();
int newTreeIndex = 0;
//insert tree
while ((combinedTrees.getData().probability >= treeArray.ElementAt(newTreeIndex).getData().probability))
{
//did we reach the end?
if (newTreeIndex == treeArray.Count - 1)
{
newTreeIndex++;
break;
}
//if not, keep looping until we find our insert point
newTreeIndex++;
}
//insert tree
treeArray.Insert(newTreeIndex, combinedTrees);
treeArray.RemoveAt(0);
treeArray.RemoveAt(0);
} //end while( >1)
treeArray.ElementAt(0).toRoot();
RootedBinaryTree <Word> combinedTree = treeArray.ElementAt(0);
string codeString = "";
assignCodes(ref codeString, theWords, combinedTree);
} //end huffman()
} //end huffman()
private static void assignCodes(ref string codeString, Word[] theWords, RootedBinaryTree <Word> combinedTree)
{ //if we can go left...
if (combinedTree.moveLeft())
{ //adjust codeword string accordingly...
codeString += '0';
if (combinedTree.getData().plainWord != null)
{ //if we have a character here....
for (int i = 0; i < theWords.Length; i++)
{ //find the character in our 'theWords' array...
if (combinedTree.getData().plainWord == theWords[i].plainWord)
{ //label this character with a codeword string
theWords[i].codeWord = codeString;
break;
}
}
}
//recusive call
assignCodes(ref codeString, theWords, combinedTree);
//back from recursion, remove a character from our codeword string
codeString = codeString.Remove(codeString.Length - 1);
} //end if(combinedTree.moveLeft())
//do the same for right sides....
if (combinedTree.moveRight())
{
codeString += '1';
if (combinedTree.getData().plainWord != null)
{
for (int i = 0; i < theWords.Length; i++)
{
if (combinedTree.getData().plainWord == theWords[i].plainWord)
{
theWords[i].codeWord = codeString;
break;
}
}
}
assignCodes(ref codeString, theWords, combinedTree);
codeString = codeString.Remove(codeString.Length - 1);
}
//explored all possibilities, move back up....
combinedTree.moveUp();
}
