public IEnumerator <int> GetEnumerator()
{
if (root == null)
{
Enumerable.Empty <int>();
}
else
{
List <int> values = new List <int>();
BinaryTreeUtilities.GetAllValues(root, values);
foreach (var item in values)
{
yield return(item);
}
}
}
public void PrintLevelOrder()
{
BinaryTreeUtilities.PrintLevelOrder(root);
}