using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

                    //Configure "active sessions"

            var rand = new Random();

            var activeSessionIds = new List<int>();

​

            for (int i = 0; i < 10000; i++)

            {

                bool addedValue = false;

                while (!addedValue)

                {

                    var newSession = rand.Next(1000, 100000);

                    if (activeSessionIds.All(_ => _ != newSession))

                    {

                        activeSessionIds.Add(newSession);

                        addedValue = true;

                    }

                }

            }

​

            var totalAttempts = 0;

            var collisions = 0;

            var misses = 0;

​

            //Check for random collisions with active sessions

            for(int i = 0; i < 100000; i++)

            {

                var randSessionId = rand.Next(1000, 100000);

                if (activeSessionIds.Any(_ => _ == randSessionId))

                    collisions++;

                else

                    misses++;

​

                totalAttempts++;

            }

​

            Console.WriteLine("Total Attempts: {0}", totalAttempts);

            Console.WriteLine("Misses: {0}", misses);

            Console.WriteLine("Collisions: {0}", collisions);

            Console.WriteLine("Probability: {0}", (decimal)collisions / totalAttempts);   

    }

}