C# Display a Binary Search Tree in Console

Question

I have simple binary search tree

public class BNode
{
    public int item;
    public BNode right;
    public BNode left;

    public BNode(int item)
    {
             


        

Answer 1

This is my take at it:

I've added PrintPretty to BNode, and I've removed the second Print function you had in BTree.

(Edit: I made the tree more lisible by changing the original chars to draw the branches of the tree)

    static void Main(string[] args)
    {
        BTree btr = new BTree();
        btr.Add(6);
        btr.Add(2);
        btr.Add(3);
        btr.Add(11);
        btr.Add(30);
        btr.Add(9);
        btr.Add(13);
        btr.Add(18);

        btr.Print();

    }

    public class BNode
    {
        public int item;
        public BNode right;
        public BNode left;

        public BNode(int item)
        {
            this.item = item;
        }

        public void PrintPretty(string indent, bool last)
        {

            Console.Write(indent);
            if (last)
            {
                Console.Write("└─");
                indent += "  ";
            }
            else
            {
                Console.Write("├─");
                indent += "| ";
            }
            Console.WriteLine(item);

            var children = new List();
            if (this.left != null)
                children.Add(this.left);
            if (this.right != null)
                children.Add(this.right);

            for (int i = 0; i < children.Count; i++)
                children[i].PrintPretty(indent, i == children.Count - 1);

        }

    }

    public class BTree
    {
        private BNode _root;
        private int _count;
        private IComparer _comparer = Comparer.Default;


        public BTree()
        {
            _root = null;
            _count = 0;
        }


        public bool Add(int Item)
        {
            if (_root == null)
            {
                _root = new BNode(Item);
                _count++;
                return true;
            }
            else
            {
                return Add_Sub(_root, Item);
            }
        }

        private bool Add_Sub(BNode Node, int Item)
        {
            if (_comparer.Compare(Node.item, Item) < 0)
            {
                if (Node.right == null)
                {
                    Node.right = new BNode(Item);
                    _count++;
                    return true;
                }
                else
                {
                    return Add_Sub(Node.right, Item);
                }
            }
            else if (_comparer.Compare(Node.item, Item) > 0)
            {
                if (Node.left == null)
                {
                    Node.left = new BNode(Item);
                    _count++;
                    return true;
                }
                else
                {
                    return Add_Sub(Node.left, Item);
                }
            }
            else
            {
                return false;
            }
        }

        public void Print()
        {
            _root.PrintPretty("", true);
        }

    }

This is the result (more compact, as I mentioned):

---

Edit: the following code has been modified in order to show the info about left-right:

    static void Main(string[] args)
    {
        BTree btr = new BTree();
        btr.Add(6);
        btr.Add(2);
        btr.Add(3);
        btr.Add(11);
        btr.Add(30);
        btr.Add(9);
        btr.Add(13);
        btr.Add(18);

        btr.Print();

    }

    public enum NodePosition
    {
        left,
        right,
        center
    }

    public class BNode
    {
        public int item;
        public BNode right;
        public BNode left;

        public BNode(int item)
        {
            this.item = item;
        }

        private void PrintValue(string value, NodePosition nodePostion)
        {
            switch (nodePostion)
            {
                case NodePosition.left:
                    PrintLeftValue(value);
                    break;
                case NodePosition.right:
                    PrintRightValue(value);
                    break;
                case NodePosition.center:
                    Console.WriteLine(value);
                    break;
                default:
                    throw new NotImplementedException();
            }
        }

        private void PrintLeftValue(string value)
        {
            Console.ForegroundColor = ConsoleColor.Magenta;
            Console.Write("L:");
            Console.ForegroundColor = (value == "-") ? ConsoleColor.Red : ConsoleColor.Gray;
            Console.WriteLine(value);
            Console.ForegroundColor = ConsoleColor.Gray;
        }

        private void PrintRightValue(string value)
        {
            Console.ForegroundColor = ConsoleColor.Green;
            Console.Write("R:");
            Console.ForegroundColor = (value == "-") ? ConsoleColor.Red : ConsoleColor.Gray;
            Console.WriteLine(value);
            Console.ForegroundColor = ConsoleColor.Gray;
        }

        public void PrintPretty(string indent, NodePosition nodePosition, bool last, bool empty)
        {

            Console.Write(indent);
            if (last)
            {
                Console.Write("└─");
                indent += "  ";
            }
            else
            {
                Console.Write("├─");
                indent += "| ";
            }

            var stringValue = empty ? "-" : item.ToString();
            PrintValue(stringValue, nodePosition);

            if(!empty && (this.left != null || this.right != null))
            {
                if (this.left != null)
                    this.left.PrintPretty(indent, NodePosition.left, false, false);
                else
                    PrintPretty(indent, NodePosition.left, false, true);

                if (this.right != null)
                    this.right.PrintPretty(indent, NodePosition.right, true, false);
                else
                    PrintPretty(indent, NodePosition.right, true, true);
            }
        }

    }

    public class BTree
    {
        private BNode _root;
        private int _count;
        private IComparer _comparer = Comparer.Default;


        public BTree()
        {
            _root = null;
            _count = 0;
        }


        public bool Add(int Item)
        {
            if (_root == null)
            {
                _root = new BNode(Item);
                _count++;
                return true;
            }
            else
            {
                return Add_Sub(_root, Item);
            }
        }

        private bool Add_Sub(BNode Node, int Item)
        {
            if (_comparer.Compare(Node.item, Item) < 0)
            {
                if (Node.right == null)
                {
                    Node.right = new BNode(Item);
                    _count++;
                    return true;
                }
                else
                {
                    return Add_Sub(Node.right, Item);
                }
            }
            else if (_comparer.Compare(Node.item, Item) > 0)
            {
                if (Node.left == null)
                {
                    Node.left = new BNode(Item);
                    _count++;
                    return true;
                }
                else
                {
                    return Add_Sub(Node.left, Item);
                }
            }
            else
            {
                return false;
            }
        }

        public void Print()
        {
            _root.PrintPretty("", NodePosition.center, true, false);
        }

    }

The result: