using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

public class Program

{

    void run(List<string> L1, List<string> L2)

    {

        double intersect = 0;

        double any = 0;

        double overlaps = 0;

​

        Stopwatch stopWatch = new Stopwatch();

​

        for (int i = 0; i < 10; i++)

        {

            stopWatch.Restart();

            Intersect(L1, L2);

            stopWatch.Stop();

            intersect += stopWatch.ElapsedMilliseconds;

​

            stopWatch.Restart();

            Any(L1, L2);

            stopWatch.Stop();

            any += stopWatch.ElapsedMilliseconds;

            stopWatch.Restart();

            Overlaps(L1.ToHashSet(), L2.ToHashSet());

            stopWatch.Stop();

            overlaps += stopWatch.ElapsedMilliseconds;

        }

​

        Console.WriteLine("Intersect: " + intersect + "ms");

        Console.WriteLine("Any: " + any + "ms");

        Console.WriteLine("HashSet.Overlaps: " + overlaps + "ms");

    }

​

    private static bool Any(List<string> lst1, List<string> lst2)

    {

        return lst1.Any(lst2.Contains);

    }

​

    private static bool Intersect(List<string> lst1, List<string> lst2)

    {

        return lst1.Intersect(lst2).Any();

    }  

    private static bool Overlaps(HashSet<string> lst1, HashSet<string> lst2)

    {

        return lst1.Overlaps(lst2);

    }  

​

    public static void Main()

    {

        // No overlap

        Console.WriteLine("No Overlap:");

        new Program().run(

            Enumerable.Range(0, 4000).Select(x => x.ToString()).ToList(), 

            Enumerable.Range(4000, 4000).Select(x => x.ToString()).ToList());

        // Overlap

        Console.WriteLine("\nOverlap:");

        new Program().run(

            Enumerable.Range(0, 4000).Select(x => x.ToString()).ToList(), 

            Enumerable.Range(0, 4000).Select(x => x.ToString()).ToList());

    }

}