public static void Main(string[] args)
{
int i;
PriorityQueue <PriorityClass> PQ = new PriorityQueue <PriorityClass>(10);
PriorityClass[] A = new PriorityClass[5];
A[0] = new PriorityClass(1, "Susan");
A[1] = new PriorityClass(3, "Hannah");
A[2] = new PriorityClass(3, "Tony");
A[3] = new PriorityClass(7, "Pranjal");
A[4] = new PriorityClass(1, "Alan");
PQ.Add(new PriorityClass(6, "Brian"));
PQ.Add(new PriorityClass(6, "Richard"));
PQ.Add(new PriorityClass(4, "Sabine"));
PQ.Add(new PriorityClass(7, "Wenying"));
PQ.Add(new PriorityClass(0, "Patrick"));
while (!PQ.Empty())
{
Console.WriteLine(PQ.Front().ToString());
PQ.Remove();
}
Console.ReadLine();
PQ.HeapSort(A);
for (i = 0; i < A.Length; i++)
{
Console.WriteLine(A[i].ToString());
}
Console.ReadLine();
}
// 20 marks
// Build a Huffman tree based on the character frequencies greater than 0 (invoked by Huffman)
private void Build(int[] F)
{
PriorityQueue.PriorityQueue <Node> PQ = new PriorityQueue.PriorityQueue <Node>(F.Length);
for (int x = 0; x < F.Length; x++) // loop to create the leaf nodes
{
if (F[x] > 0) // checks to make sure there is at least one occurrence
{
Node temp = new Node(possibleCharacters[x], F[x], null, null); // leaf nodes have no left and right nodes
PQ.Add(temp); //add leaf nodes to priority queue
}
}
while (PQ.Size() > 2)
{
Node temp = new Node(); //new empty node
int freq = PQ.Front().Frequency; //store left side frequency
temp.Left = PQ.Front(); // store left side node
PQ.Remove(); //remove left side node from priority queue
temp.Frequency = freq + PQ.Front().Frequency; //store left side freq plus right side freq
temp.Right = PQ.Front(); //store right side node
PQ.Remove(); //remove right side node from priority queue
PQ.Add(temp); //add new sub tree to priority queue
}
if (PQ.Size() == 2)
{
HT = new Node(); //initialize head node as empty
int freq = PQ.Front().Frequency; //store left node frequency
HT.Left = PQ.Front(); // store left node
PQ.Remove(); // remove node from priority queue
HT.Frequency = freq + PQ.Front().Frequency; //store both frequencies in head node
HT.Right = PQ.Front(); //store right node
PQ.MakeEmpty(); //remove node from priority queue (make sure its empty)
}
else //Special case, only one node in the priority queue
{
HT = new Node(); // head node is set to only have one leaf node and freq is that of the leaf node
HT.Frequency = PQ.Front().Frequency; // set head node freq as leaf node freq
HT.Left = PQ.Front(); // if there is only one node, it becomes the head node
PQ.MakeEmpty(); //empty priority queue
}
}
// Method : Build
// Parameters: Dictionary of characters and their frequency
// Return Type : Void
/* Description: Given a dictionary, we build a tree using the Priority Queue
* where 2 nodes with the highest priority are removed. */
private void Build(Dictionary <char, int> charDictionary)
{
// Implementing priority queue class and using it's methods to mainpulate the huffman tree
PriorityQueue <Node> PQ;
PQ = new PriorityQueue <Node>(charDictionary.Count); // Creating a priority queue of Nodes
// Based on the size of the dictionary(char,frequency)
foreach (KeyValuePair <char, int> entry in charDictionary) // Adding each character as a node
{
Node q;
q = new Node(entry.Key, entry.Value, null, null);
PQ.Add(q); // Creating leaf nodes
}
/* To create root nodes, HT gets put back into the queue each time until size !=1*/
while (PQ.Size() != 1)
{
// Removing the two highest priority nodes
// Less frequent == higher priority
Node x = PQ.Front();
PQ.Remove();
Node y = PQ.Front();
PQ.Remove();
// Error checking if user enters nothing
if (x == null || y == null)
{
throw new ArgumentException("Input cannot be empty, exiting program.");
}
// Forming a root node by adding the removed nodes frequency
HT = new Node(default(char), x.Frequency + y.Frequency, x, y);
PQ.Add(HT);
}
HT = PQ.Front(); // First node in the queue will be the tree created with all the left and right references
}
