using System;

using System.Diagnostics;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main() { Linq.Run(null); }

}

​

public class Linq

{

    public static void Run(string[] args) { Grouping(args); }

​

    private static void Grouping(string[] args)

    {

        Stopwatch now = new Stopwatch();

​

        now.Start();

​

        Person[] Persons = Person.Persons;

​

        now.Stop();

​

        Console.WriteLine("Created , Count = {0} and Time = {1}ms",

                          Persons.Length.ToString("N"),now.ElapsedMilliseconds);

​

        now.Restart();

​

        var it = from p in Persons group p by p.Job;

        var result=it.ToArray();

        now.Stop();

​

        Console.WriteLine("Grouped , Count = {0} and Time = {1}ms and Ticks = {2}",

                         it.Count(),now.ElapsedMilliseconds,now.ElapsedTicks);

    }

}

​

public class Person

{

    // change to 300

    private const int GroupCount = 30;

​

    // change to 1000000

    static int PersonCount = 1000;

​

    static int Shuffling = 10000;

​

    public int Id = 0;

​

    public string Name = "";

​

    public string Job = "";

​

    public Person(int id, string name, string job)

    {

        Id = id;

        Name = name;

        Job = job;

    }

​

    public void Shuffle(Person it)

    {

        int i = it.Id;

        it.Id = Id;

        Id = i;

​

        string s = it.Name;

        it.Name = s;

        Name = s;

​

        s = it.Job;

        it.Job = s;

        Job = s;

    }

​

    public static Person[] Persons

    {

        get

        {

            Random random = new Random();

​

            List<Person> Box = new List<Person>();

​

            for (int x = 0; x < GroupCount; x++)

            {

                string job = x.ToString() + ":" + random.Next(10000, 40000).ToString();

                for (int y = 0; y < PersonCount; y++)

                {

                    Box.Add(new Person(y, y.ToString(), job));

                }

            }

​

            int max = GroupCount * PersonCount;

            for (int x = 0; x < Shuffling; x++)

            {

                int one = random.Next(0, max);

                int two = random.Next(0, max);

​

                Box[one].Shuffle(Box[two]);

            }

​

            return Box.ToArray();

        }

    }

}