public static string Perform(string text)
{
var chars = text.ToCharArray();
// Gathering alphabet frequency
var alphabetFrequency = new Dictionary <char, int>();
foreach (var c in chars) // First pass through the char array
{
if (!alphabetFrequency.ContainsKey(c))
{
alphabetFrequency.Add(c, 1);
}
else
{
alphabetFrequency[c] = alphabetFrequency[c] + 1;
}
}
// Create binary heap
var priorityQueue = new BinaryHeapPriorityQueue <TreeNode>(alphabetFrequency.Count, (i1, i2) => i2.Count.CompareTo(i1.Count));
foreach (var entry in alphabetFrequency)
{
var leafNode = new LeafTreeNode(entry.Value);
CharToNodes.Add(entry.Key, leafNode);
priorityQueue.Insert(leafNode); // Initially PQ contains only leaf nodes
}
// Main part of the algorithm
while (priorityQueue.GetSize() > 1)
{
var n1 = priorityQueue.Extract();
var n2 = priorityQueue.Extract();
var innerNode = new InnerTreeNode(n1, n2); // Creates a new node with sum of frequencies...
priorityQueue.Insert(innerNode); // ...and put it back
} // Repeat the procedure untill PQ has only one element
var root = priorityQueue.Extract(); // Take the last element (root) from the PQ
root.CreateCode(alphabetFrequency.Count == 1 ? "0" : ""); // Build codes for the whole hierarchy
var sb = new StringBuilder();
foreach (var t in chars) // Second pass through the char array
{
var c = CharToNodes[t].Code;
sb.Append(c);
}
return(sb.ToString());
}
public void Extract_ValidParamsPassed_Success()
{
IPriorityQueue <int> priorityQueue = new BinaryHeapPriorityQueue <int>(5, (x, y) => - x.CompareTo(y));
priorityQueue.Insert(5);
priorityQueue.Insert(4);
priorityQueue.Insert(3);
priorityQueue.Insert(2);
priorityQueue.Insert(1);
var v1 = priorityQueue.Extract();
var v2 = priorityQueue.Extract();
var v3 = priorityQueue.Extract();
var v4 = priorityQueue.Extract();
var v5 = priorityQueue.Extract();
Assert.AreEqual(v1, 1);
Assert.AreEqual(v2, 2);
Assert.AreEqual(v3, 3);
Assert.AreEqual(v4, 4);
Assert.AreEqual(v5, 5);
}
public void Extract_StringDataType_Success()
{
IPriorityQueue <string> priorityQueue = new BinaryHeapPriorityQueue <string>(10, (x, y) => - string.Compare(x, y, StringComparison.Ordinal));
priorityQueue.Insert("Z");
priorityQueue.Insert("X");
priorityQueue.Insert("Y");
priorityQueue.Insert("W");
priorityQueue.Insert("V");
priorityQueue.Insert("U");
priorityQueue.Insert("T");
priorityQueue.Insert("S");
priorityQueue.Insert("R");
priorityQueue.Insert("Q");
var v1 = priorityQueue.Extract();
var v2 = priorityQueue.Extract();
var v3 = priorityQueue.Extract();
var v4 = priorityQueue.Extract();
var v5 = priorityQueue.Extract();
var v6 = priorityQueue.Extract();
var v7 = priorityQueue.Extract();
var v8 = priorityQueue.Extract();
var v9 = priorityQueue.Extract();
var v10 = priorityQueue.Extract();
Assert.AreEqual(v1, "Q");
Assert.AreEqual(v2, "R");
Assert.AreEqual(v3, "S");
Assert.AreEqual(v4, "T");
Assert.AreEqual(v5, "U");
Assert.AreEqual(v6, "V");
Assert.AreEqual(v7, "W");
Assert.AreEqual(v8, "X");
Assert.AreEqual(v9, "Y");
Assert.AreEqual(v10, "Z");
}
public void Extract_StringDataTypeDifferentOrder_Success()
{
IPriorityQueue <string> priorityQueue = new BinaryHeapPriorityQueue <string>(10, (x, y) => string.Compare(x, y, StringComparison.Ordinal));
priorityQueue.Insert("A");
priorityQueue.Insert("B");
priorityQueue.Insert("C");
priorityQueue.Insert("D");
priorityQueue.Insert("E");
priorityQueue.Insert("F");
priorityQueue.Insert("G");
priorityQueue.Insert("H");
priorityQueue.Insert("I");
priorityQueue.Insert("J");
var v1 = priorityQueue.Extract();
var v2 = priorityQueue.Extract();
var v3 = priorityQueue.Extract();
var v4 = priorityQueue.Extract();
var v5 = priorityQueue.Extract();
var v6 = priorityQueue.Extract();
var v7 = priorityQueue.Extract();
var v8 = priorityQueue.Extract();
var v9 = priorityQueue.Extract();
var v10 = priorityQueue.Extract();
Assert.AreEqual(v1, "J");
Assert.AreEqual(v2, "I");
Assert.AreEqual(v3, "H");
Assert.AreEqual(v4, "G");
Assert.AreEqual(v5, "F");
Assert.AreEqual(v6, "E");
Assert.AreEqual(v7, "D");
Assert.AreEqual(v8, "C");
Assert.AreEqual(v9, "B");
Assert.AreEqual(v10, "A");
}