using System;

using System.Collections.Generic;

using System.Diagnostics;

public class Program

{

    const int _max = 10000000;

    public static void Main()

    {

        var h = new HashSet<string>(StringComparer.Ordinal);

        var d = new Dictionary<string, bool>(StringComparer.Ordinal);

        var a = new string[] { "a", "b", "c", "d", "longer", "words", "also" };

​

        var s1 = Stopwatch.StartNew();

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

        {

            foreach (string s in a)

            {

                h.Add(s);

                h.Contains(s);

            }

        }

        s1.Stop();

        var s2 = Stopwatch.StartNew();

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

        {

            foreach (string s in a)

            {

                d[s] = true;

                d.ContainsKey(s);

            }

        }

        s2.Stop();

        Console.WriteLine(h.Count);

        Console.WriteLine(d.Count);

        Console.WriteLine("HashSet ====> " + ((double)(s1.Elapsed.TotalMilliseconds * 1000000) /_max).ToString("0.00 ns"));

        Console.WriteLine("Dictionary ====> " + ((double)(s2.Elapsed.TotalMilliseconds * 1000000) /_max).ToString("0.00 ns"));

    }

}