using System;

using System.Linq;

using System.Xml.Linq;

public class Program

{

    public static void Main()

    {

        string xmlString = """<root> <level1 name="A"> <level2 name="A1"/> <level2 name="A2"/> </level1> <level1 name="B"> <level2 name="B1"/> <level2 name="B2"/> </level1> <level1 name="C"/></root>""";

        XDocument doc = XDocument.Parse(xmlString);

        // Select the level1 elements from the document and create an anonymous object for each element

        // with a Name property containing the value of the "name" attribute and a Children property

        // containing a collection of the names of the level2 elements

        var results = doc.Descendants("level1")

                        .Select(level1 => new

                        {

                            Name = level1.Attribute("name").Value,

                            Children = level1.Descendants("level2")

                                             .Select(level2 => level2.Attribute("name").Value)

                        });

​

        // Iterate through the results and write the Name and Children properties to the console

        foreach (var result in results)

        {

            Console.WriteLine(result.Name);

            foreach (var child in result.Children)

                Console.WriteLine("  " + child);

        }

    }

}