Binary Sort Tree with example use

Program.cs

using System.Collections;

// var root = new Node<int>(10);
var root = new Node<int>(10, NumberComparer);
root.Insert(9);
root.Insert(5);
root.Insert(15);
root.Insert(3);
root.Insert(9);
root.Insert(7);
root.Insert(12);
root.Insert(18);

// root.Traverse();

// foreach (var value in root)
//     Console.WriteLine(value);

Console.WriteLine($"Length: {root.Length}");
Console.WriteLine(root.ToString());

static int NumberComparer(int a, int b) => a.CompareTo(b) * -1;

public class Node<T>(T value, Func<T, T, int>? comparer = null) : IEnumerable<T> where T : IComparable<T>
{
    public T Value = value;
    public Node<T>? Left;
    public Node<T>? Right;
    public int Length { get; private set; } = 1;
    private readonly Func<T, T, int>? Comparer = comparer;

    public IEnumerator<T> GetEnumerator()
    {
        if (Left != null)
            foreach (var value in Left)
                yield return value;

        yield return Value;

        if (Right != null)
            foreach (var value in Right)
                yield return value;
    }

    public void Insert(T newValue)
    {
        Length++;

        var compared = Comparer == null ? newValue.CompareTo(Value) : Comparer(newValue, Value);

        if (compared < 0)
        {
            if (Left == null)
                Left = new Node<T>(newValue, Comparer);
            else
                Left.Insert(newValue);
        }
        else
        {
            if (Right == null)
                Right = new Node<T>(newValue, Comparer);
            else
                Right.Insert(newValue);
        }
    }

    public string ToString(string separator = ",") => String.Join(separator, this.ToArray<T>());

    IEnumerator IEnumerable.GetEnumerator() => throw new NotImplementedException();
}