public IEnumerable <T> PreOrden()
{
yield return(Key);
if (Left != null)
{
var l = Left.PreOrden();
foreach (var item in l)
{
yield return(item);
}
}
if (Rigth != null)
{
var r = Rigth.PreOrden();
foreach (var item in r)
{
yield return(item);
}
}
}
/// <summary>
/// The pre-order walk on tree
/// </summary>
/// <returns></returns>
public IEnumerable <T> PreOrden()
{
return(Count > 0 ? C_Root.PreOrden() : C_Root.EmptyEnum());
}