public void Build(string source)
{
for ( int i = 0; i < source.Length; i++ ) {
if ( !Frequencies.ContainsKey( source[i] ) ) {
Frequencies.Add( source[i], 0 );
}
Frequencies[source[i]]++;
}
foreach ( KeyValuePair<char, int> symbol in Frequencies ) {
nodes.Add( new HuffmanNode() { Symbol = symbol.Key, Frequency = symbol.Value } );
}
while ( nodes.Count > 1 ) {
List<HuffmanNode> orderedNodes = nodes.OrderBy( node => node.Frequency ).ToList<HuffmanNode>();
if ( orderedNodes.Count >= 2 ) {
// Take first two items
List<HuffmanNode> taken = orderedNodes.Take( 2 ).ToList<HuffmanNode>();
// Create a parent node by combining the frequencies
HuffmanNode parent = new HuffmanNode() {
Symbol = '*',
Frequency = taken[0].Frequency + taken[1].Frequency,
Left = taken[0],
Right = taken[1]
};
nodes.Remove( taken[0] );
nodes.Remove( taken[1] );
nodes.Add( parent );
}
this.Root = nodes.FirstOrDefault();
}
}
public bool IsLeaf(HuffmanNode node)
{
return ( node.Left == null && node.Right == null );
}