using System;

using System.Collections.Generic;

using System.Linq;

​

​

public class Product

{

    public int Id {get;set;}

    public string Role {get;set;}

    public string Publisher {get;set;}

}

public class Contributor

{

    public string Id {get;set;}

    public string Name {get;set;}

    public Product[] ProductsContributedTo {get;set;}

}

​

public class Program

{

    public static List<Contributor> contributors = new List<Contributor>();

    public static void Main()

    {

        contributors.Add(

            new Contributor() {

                Id = "1-1",

                Name = "Barry Collins",

                ProductsContributedTo = new Product[] { 

                    new Product() {Id = 1, Role = "Author", Publisher = "Maybridge"},

                    new Product() {Id = 10, Role = "Author", Publisher = "Persons"}

                }

            }

        );

        contributors.Add(

            new Contributor() {

                Id = "2-1",

                Name = "Maggie Fenwick",

                ProductsContributedTo = new Product[] {

                    new Product() {Id = 2, Role = "Author", Publisher = "Maybridge"},

                    new Product() {Id = 3, Role = "Illustrator", Publisher = "Boom Town"}

                }

            }

        );

        contributors.Add(

            new Contributor() {

                Id = "2-1",

                Name = "Sedgewick F0ley",

                ProductsContributedTo = new Product[] {

                    new Product() {Id = 4, Role = "Illustrator", Publisher = "Boom Town"},

                    new Product() {Id = 5, Role = "Illustrator", Publisher = "Boom Town"}

                }

            }

        );

        List<Contributor> authors = contributors.SelectMany(people => people.ProductsContributedTo

                                  .Where(product => product.Role == "Author")

                                  .Select(c => people))

                                  .ToList();

        foreach(var person in authors)

        {

            Console.WriteLine("Author is " + person.Name + " and contributes to: ");

            foreach(var product in person.ProductsContributedTo)

            {

                if(product.Role == "Author")

                {

                  Console.WriteLine("CORRECT Id: " + product.Id + " - Role: " + product.Role);

                }

                if(product.Role != "Author")

                {

                  Console.WriteLine("INCORRECT Id: " + product.Id + " - Role: " + product.Role);

                }

            }

        }

    }

}