using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var websites = new List<string>

        {

            "google.com",

            "www.google.com",

            "https://www.google.com",

            "http://www.google.com",

            "w..com",

            "w..com.."

        };      

        foreach(var website in websites)

        {

            Console.WriteLine(IsValidWebsite(website));

        }

    }

​

    private static bool IsValidWebsite(string website)

    {

        Uri uriResult;

        if(!website.StartsWith(Uri.UriSchemeHttp))

        {

            website = string.Format("{0}://{1}", Uri.UriSchemeHttp, website);

        }

        return Uri.TryCreate(website, UriKind.Absolute, out uriResult) 

            && (uriResult.Scheme == Uri.UriSchemeHttp || uriResult.Scheme == Uri.UriSchemeHttps);

    }

}