using System;

•using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(ConvertCategoryTreeToCategoryQueryResult(new [] { "Frimärken", "Frimärken Sverige", "Frimärken Stockholm" }));

    }

    private static Category ConvertCategoryTreeToCategoryQueryResult(IList<string> categoryTree)

    {

        var category = (Category)null;

        var siblings = new List<Category>();

        var id = 0;

​

        foreach (var name in categoryTree)

        {

            var parent = category;

            var children = siblings;

​

            category = new Category(++id, name, 0, parent, children);

            siblings = new List<Category> { category };

        }

​

        return category;

    }

​

    public class Category

    {

        public Category(int id, string name, int unknown, Category parent, List<Category> children) {

            var childrenStringRepresentations = string.Join('\n', children);

            var childrenIds = string.Join(',', children.Select(x => x.Id));

            Id = id;

            StringRepresentation = $"Id={id} Name={name.PadRight(30, ' ')} Unknown={unknown} Parent={parent?.Id} Children=[{childrenIds}]\n{childrenStringRepresentations}";

        }

        public int? Id { get; }

        public string StringRepresentation { get; }

        public override string ToString()

        {

            return StringRepresentation;

        }

    }

}