using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public class Result

    {

        public int user_id { get; set; }

        public int sample_id { get; set; }

        public int machine_id { get; set; }

    }

    public static void Main()

    {

        int selectedUserId = 1;

        List<Result> results = new()

        {

            // user 2:

            new() { user_id = 2, sample_id = 1, machine_id = 4 },

            new() { user_id = 2, sample_id = 1, machine_id = 2026 },

            new() { user_id = 2, sample_id = 1, machine_id = 2030 },

            new() { user_id = 2, sample_id = 1, machine_id = 2046 },

            new() { user_id = 2, sample_id = 1, machine_id = 2053 },

            new() { user_id = 2, sample_id = 1, machine_id = 2058 },

            new() { user_id = 2, sample_id = 1, machine_id = 2061 },

            // user 1:

            new() { user_id = 1, sample_id = 1, machine_id = 4 },

            new() { user_id = 1, sample_id = 1, machine_id = 2026 },

            new() { user_id = 1, sample_id = 1, machine_id = 2030 },

            new() { user_id = 1, sample_id = 1, machine_id = 2046 },

            new() { user_id = 1, sample_id = 1, machine_id = 2053 },

            new() { user_id = 1, sample_id = 1, machine_id = 2058 },

            new() { user_id = 1, sample_id = 1, machine_id = 2061 },

            new() { user_id = 1, sample_id = 1, machine_id = 2080 }, 

            new() { user_id = 1, sample_id = 1, machine_id = 2081 },

            new() { user_id = 1, sample_id = 1, machine_id = 2083 },

            new() { user_id = 1, sample_id = 1, machine_id = 2084 }

        };

        var filteredEarly = results

            .Where(r => r.user_id == selectedUserId) // <--

            .GroupBy(r => new { r.machine_id, r.sample_id })

            .Select(r => r.First());

        var filteredLate = results

            .GroupBy(r => new { r.machine_id, r.sample_id })

            .Select(r => r.First())

            .Where(r => r.user_id == selectedUserId); // <--

        Console.WriteLine("user_id   sample_id   machine_id");

        Console.WriteLine("--------------------------------");

        Console.WriteLine("\nApplying filtering early:\n");

        Print(filteredEarly);

        Console.WriteLine("\nApplying filtering late:\n");

        Print(filteredLate);

    }

    private static void Print(IEnumerable<Result> results)

    {

        foreach (var item in results)

        {

            Console.WriteLine($"{item.user_id.ToString().PadRight(10)}{item.sample_id.ToString().PadRight(12)}{item.machine_id}");

        }

    }

}