Zadanie z Linq C#

Question

using System;
using System.Collections.Generic;
using System.Linq;


namespace LINQ2
{
    class Program
    {

        static List<Customer> Customers = new List<Customer>();
        static List<Notebook> Notebooks = new List<Notebook>();
        static List<Order> Orders = new List<Order>();

        static void Main(string[] args)
        {
            PopulateData();
			
			
		}
		
		
		
        private static void PopulateData()
        {
            int c = 30;
            string[] firstNames = { "John", "Pluto", "Scooby-Doo", "Burek", "Szarik" };
            string[] lastNames = { "Lipowski", "Bukowski", "Dębowski", "Sosnowski", "Świerkowski" };
            string[] cities = { "Bestwina", "Kaniów", "Ligota", "Meszna", "Godziszka" };
            string[] countries = { "PL", "SK", "CZ", "LT", "DE" };
            Random R = new Random();

            for (int i = 0; i < c; i++)
            {
                Customers.Add(new Customer()
                {
                    CustomerId = i,
                    FirstName = firstNames[R.Next(5)],
                    LastName = lastNames[R.Next(5)],
                    Addr = new Address() { City = cities[R.Next(5)], Country = countries[R.Next(5)] }
                });
            }

            string[] makers = { "HP", "IBM", "MSI", "Dell" };
            string[] cpus = { "i3", "i5", "i7", "Xeon E5" };

            for (int i = 0; i < c; i++)
            {
                Notebooks.Add(new Notebook()
                {
                    ComputerId = i,
                    Make = makers[R.Next(4)],
                    Price = 1000 + 100 * i,
                    RAM = (int)Math.Pow(2, R.Next(6)),
                    CPU = cpus[R.Next(4)],
                    Drive = (int)Math.Pow(2, R.Next(6))
                });
            }

            for (int i = 0; i < 2*c; i++)
            {
                Orders.Add(new Order()
                {
                    OrderId = i,
                    Date = DateTime.Now.AddDays(-1000*R.NextDouble()),
                    CustomerId = R.Next(c),
                    ProductIdQt = new Dictionary<int, int>() { { R.Next(0, 10), R.Next(10) }, 
					             { R.Next(10, 20), R.Next(10) }, { R.Next(20, 30), R.Next(10) } }
                });
            }

        }
    }

    class Customer
    {
        public int CustomerId;
        public string FirstName, LastName;
        public Address Addr;
    }

    class Address
    {
        public string City, Country;
    }

    class Order
    {
        public DateTime Date;
        public int OrderId, CustomerId;
        public Dictionary<int, int> ProductIdQt;
    }

    class Notebook
    {
        public int ComputerId;
        public string Make;
        public double Price;
        public int RAM, Drive;
        public string CPU;
    }
	
}

Mam program napisany w C# słabo ogarniam linq a potrzebuje zapytania mieć do tego programu. Napisz tu kilka zapytań LINQ, np. wypisz wszystkich użytkowników mieszkających w Polsce, którzy kupili łącznie co najmniej 3 notobooki oraz inne zapytania.

Answer 1

po pierwsze radzę używać propercji zamiast  public int ComputerId;.
 pisane na kolenie ale powinno działać

 

            var list = new List<int>();
            var polacy = Customers.Where(x => x.Addr.Country == "PL");
            foreach (var item in polacy)
            {
                if (Orders.Count(x => x.CustomerId == item.CustomerId)> 3)
                {
                    list.Add(item.CustomerId);
                }
            }