在C#中删除BST的功能

using System;

public class TreeNode
{
    public int val;
    public TreeNode left;
    public TreeNode right;

    public TreeNode(int val)
    {
        this.val = val;
        left = null;
        right = null;
    }
}

public class BST
{
    private TreeNode root;

    public BST()
    {
        root = null;
    }

    public void Insert(int val)
    {
        root = InsertNode(root, val);
    }

    private TreeNode InsertNode(TreeNode node, int val)
    {
        if (node == null)
        {
            return new TreeNode(val);
        }

        if (val < node.val)
        {
            node.left = InsertNode(node.left, val);
        }
        else if (val > node.val)
        {
            node.right = InsertNode(node.right, val);
        }

        return node;
    }

    public void Delete(int val)
    {
        root = DeleteNode(root, val);
    }

    private TreeNode DeleteNode(TreeNode node, int val)
    {
        if (node == null)
        {
            return null;
        }

        if (val < node.val)
        {
            node.left = DeleteNode(node.left, val);
        }
        else if (val > node.val)
        {
            node.right = DeleteNode(node.right, val);
        }
        else
        {
            if (node.left == null && node.right == null)
            {
                // Case 1: 要删除的节点是叶子节点
                node = null;
            }
            else if (node.left == null)
            {
                // Case 2: 要删除的节点只有右子节点
                node = node.right;
            }
            else if (node.right == null)
            {
                // Case 2: 要删除的节点只有左子节点
                node = node.left;
            }
            else
            {
                // Case 3: 要删除的节点有两个子节点
                TreeNode successor = FindMin(node.right);
                node.val = successor.val;
                node.right = DeleteNode(node.right, successor.val);
            }
        }

        return node;
    }

    private TreeNode FindMin(TreeNode node)
    {
        while (node.left != null)
        {
            node = node.left;
        }

        return node;
    }
}

public class Program
{
    public static void Main(string[] args)
    {
        BST bst = new BST();
        bst.Insert(5);
        bst.Insert(3);
        bst.Insert(7);
        bst.Insert(2);
        bst.Insert(4);
        bst.Insert(6);
        bst.Insert(8);

        Console.WriteLine("BST before deletion:");
        InorderTraversal(bst.root);

        bst.Delete(3);

        Console.WriteLine("BST after deletion:");
        InorderTraversal(bst.root);
    }

    private static void InorderTraversal(TreeNode node)
    {
        if (node != null)
        {
            InorderTraversal(node.left);
            Console.Write(node.val + " ");
            InorderTraversal(node.right);
        }
    }
}