/// <summary>
/// Builds a Huffman tree out of the given frequencies.
/// </summary>
/// <param name="freq">Array of frequencies for a byte at index of byte</param>
/// <param name="numberOfNodes">Returns number of nodes in Huffman tree</param>
/// <returns>A fully loaded Huffman tree.</returns>
private BinaryTreeNode<byte> BuildHuffmanTree(long[] freq, out int numberOfNodes)
{
MinPriorityQueue<BinaryTreeNode<byte>> pq = new MinPriorityQueue<BinaryTreeNode<byte>>();
int count = 0;
for (int i = 0; i < freq.Length; i++)
{
if (freq[i] != 0)
{
BinaryTreeNode<byte> tmp = new BinaryTreeNode<byte>();
tmp.RootValue = (byte)i;
pq.AddElement(tmp, freq[i]);
}
}
while (pq.Count > 1)
{
BinaryTreeNode<byte> root = new BinaryTreeNode<byte>();
root.IsEmpty = false;
int weight1 = (int)pq.LowestPriority;
BinaryTreeNode<byte> child1 = pq.RemoveLowestPriority();
child1.IsEmpty = false;
int weight2 = (int)pq.LowestPriority;
BinaryTreeNode<byte> child2 = pq.RemoveLowestPriority();
child2.IsEmpty = false;
root.LeftChild = child1;
root.RightChild = child2;
pq.AddElement(root, weight1 + weight2);
count++;
}
numberOfNodes = count + 1;
BinaryTreeNode<byte> huf = pq.RemoveLowestPriority();
return huf;
}