Unity相关笔试题 实现一个简单的xml解析器，实现树状打印即可，不要使用第三方库，只允许自己分析字符串

实现一个简单的xml解析器，实现树状打印即可，不要使用第三方库，只允许自己分析字符串。编程语言不限。
（GPT提供的答案）

<test>
  "main"
  <a1 key1="hoolai1" key2="company1"/>
  <name1 key1="super1">"cctv1"</name1>
  <int1>666 </int1>
      <second>
      <a2 key1="hoolai2" key2="company2"/>
      <name2 key1="super2">"cctv2"</name2>
      <int2>777 </int2>
      </second>
  <char1> "c" </char1>
</test>

sing System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml;

namespace 简单xml解析器
{
    class Node
    { 
     public string Name { get; set; }
        public List<Node> Children { get; private set; } = new List<Node>();
    public Node Parent { get; set; }
        public Node(string name, Node parent)
        {
            this.Name = name;
            this.Parent = parent;
        }

    }

    class Program
    {

        static Node Parse(string xml)
        {
            var stack = new Stack<Node>();  // 存储解析过程中的节点栈
            Node current = null;  // 当前正在解析的节点

            for (int i = 0; i < xml.Length; i++)
            {
                if (xml[i] == '<')
                {
                    // 开始标签
                    int tagStart = i + 1;
                    int tagEnd = xml.IndexOf('>', tagStart);

                    if (tagEnd < 0) throw new Exception("Invalid XML");

                    if (xml[tagStart] == '/')
                    {
                        // 结束标签
                        if (stack.Count == 0) throw new Exception("Invalid XML");

                        current = stack.Pop();
                        int tagNameStart = tagStart + 1;
                        int tagNameEnd = tagEnd;
                        if (xml.Substring(tagNameStart, tagNameEnd - tagNameStart) != current.Name)
                            throw new Exception("Invalid XML");
                    }
                    else if (xml[tagEnd - 1] == '/')
                    {
                        // 自闭合标签
                        string tagName = xml.Substring(tagStart, tagEnd - tagStart - 1);
                        var node = new Node(tagName, current);
                        current.Children.Add(node);
                    }
                    else
                    {
                        // 开始标签（非自闭合）
                        string tagName = xml.Substring(tagStart, tagEnd - tagStart);
                        var node = new Node(tagName, current);
                        stack.Push(node);
                        if (current != null) current.Children.Add(node);
                        current = node;
                    }

                    i = tagEnd;
                }
                else if (xml[i] == '>')
                {
                    // 结束标签，啥也不用干
                }
                else
                {
                    // 文本节点
                    int textStart = i;
                    int textEnd = xml.IndexOf('<', textStart);

                    if (textEnd < 0) throw new Exception("Invalid XML");

                    string text = xml.Substring(textStart, textEnd - textStart)
                                     .Trim('\n', '\r', ' ', '\t');
                    if (text.Length > 0) current.Children.Add(new Node(text, current));

                    i = textEnd - 1;
                }
            }

            return current;
        }


        static void Print(Node root, string indent)
        {
            Console.WriteLine("{0}<{1}>", indent, root.Name);
            foreach (var child in root.Children)
                Print(child, indent + "   ");
            Console.WriteLine("{0}<{1}>", indent, root.Name);
        }

        static void Main(string[] args)
        {
            //XmlDocument doc = new XmlDocument();
            string xml;
            using (StreamReader sr = new StreamReader(@"F:\学习资料\example.xml"))
            {
                xml= sr.ReadToEnd();
                Console.WriteLine(xml);
            }

            var root = Parse(xml);
            Print(root, "");
        }
    }
}