using System;

using System.Collections.Generic;

using System.Diagnostics;

public class Program

{

    public static void Main()

    {

        // Create list of 10000 random numbers

        var size = 10000;

        var rnd = new Random();

        var idList = new List<int>();

        for (var i = 0; i < size; i++)

        {

            idList.Add(rnd.Next());

        }

        // Conduct test to remove and readd random number from the list. Repeat 1000 times. Accumulate the time taken and report results

        var iterationCount = 1000;

        var stopwatch = new Stopwatch();

        // run test 1000 times and accumulate total time

        for (var i = 0; i < iterationCount; i++)

        {

            var indexToGet = rnd.Next(size);

            var numToGet = idList[indexToGet];

            stopwatch.Start();

            if (idList.Contains(numToGet))

            {

                idList.Remove(numToGet);

                idList.Add(numToGet);

            }

            stopwatch.Stop();

        }

        double averageMilliseconds = stopwatch.ElapsedMilliseconds / (double)iterationCount;

        Console.WriteLine(String.Format("total elapsed milliseconds for {0} iterations: {1}", iterationCount, stopwatch.ElapsedMilliseconds));

        Console.WriteLine(String.Format("average milliseconds for each iteration: {0}", averageMilliseconds));

    }

}