public void AddLetter(char letter)
{
if (_nodes.ContainsKey(letter))
{
throw new ArgumentException("Key already exist!");
}
_nodes[letter] = new PrefixNode(Word + letter);
}
private static IEnumerable <string> EnumerateWords(PrefixNode node)
{
if (node.IsEndOfWord)
{
yield return(node.Word);
}
foreach (var nextNode in node.GetNextNodes())
{
foreach (var result in EnumerateWords(nextNode))
{
yield return(result);
}
}
}