private static CharEntryNode GetMin(List <CharEntryNode> charEntryNodes)
{
CharEntryNode minCharEntry = charEntryNodes
.First(ce => ce.RepetitionsSum == charEntryNodes.Min(cen => cen.RepetitionsSum));
charEntryNodes.Remove(minCharEntry);
return(minCharEntry);
}
private static Dictionary <char, string> FormeEcryptingTable(CharEntryNode rootCharEntry,
List <CharEntry> charEntries)
{
Dictionary <char, string> encryptingTable = charEntries
.ToDictionary(ce => ce.Character, ce => (string)null);
FormEncodingTableInternal(encryptingTable, rootCharEntry, "");
return(encryptingTable);
}
public static string Encrypt(string source)
{
char[] sourceCharacters = source.ToCharArray();
List <CharEntry> charEntries = Parse(sourceCharacters);
CharEntryNode rootCharEntry = FormTree(charEntries);
Dictionary <char, string> encryptingTable = FormeEcryptingTable(rootCharEntry, charEntries);
return(EncryptInternal(sourceCharacters, encryptingTable));
}
private static CharEntryNode FormTreeInternal(List <CharEntryNode> charEntryNodes)
{
while (charEntryNodes.Count() != 1)
{
CharEntryNode oneCharEntry = GetMin(charEntryNodes);
CharEntryNode twoCharEntry = GetMin(charEntryNodes);
CharEntryNode charEntryNode = new CharEntryNode(oneCharEntry, twoCharEntry,
oneCharEntry.Value + twoCharEntry.Value,
oneCharEntry.RepetitionsSum + twoCharEntry.RepetitionsSum);
charEntryNodes.Add(charEntryNode);
}
return(charEntryNodes.First());
}
private static void FormEncodingTableInternal(Dictionary <char, string> encryptingTable,
CharEntryNode charEntry, string encoding)
{
if (charEntry.LeftNode != null)
{
FormEncodingTableInternal(encryptingTable, charEntry.LeftNode, encoding + "0");
}
if (charEntry.RightNode != null)
{
FormEncodingTableInternal(encryptingTable, charEntry.RightNode, encoding + "1");
}
if (charEntry.LeftNode == null && charEntry.RightNode == null)
{
encryptingTable[Convert.ToChar(charEntry.Value)] = encoding;
}
}