using System;

using System.Diagnostics;

using System.Linq;

using System.Collections.Generic;

public class Program

{

        public static void Main(string[] args)

        {

            var count = 10000000;

            //var hash = new HashSet<int>{1,2,3,4,5};

            var array = new int[]{1,2,3,4,5};

            Console.WriteLine("hash.Contains(1): {0} ms", DoTest(count, () =>

            {

                var hash = new HashSet<int>(array);

                hash.Contains(1);

            }).ToString());

​

            Console.WriteLine("array.Contains(1): {0} ms", DoTest(count, () =>

            {

                array.Contains(1);

            }).ToString());

        }

​

        static long DoTest(int count, Action action)

        {

            var sw = Stopwatch.StartNew();

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

            {

                action();

            }

            return sw.ElapsedMilliseconds;

        }

}