C# Online Compiler | .NET Fiddle

using System;
using System.ComponentModel.DataAnnotations;

namespace FindFreePlaceMvcApp
{
	public class ViewModel
	{
		[Required]
		[MinLength(10)]
		[MaxLength(100)]
		[Display(Name = "Places")]
		[RegularExpression(@"([tfTF]+)", ErrorMessage = "Invalid bool array")]
		public string Places
		{
			get;
			set;
		}

		[Required]
		[Display(Name = "IsRotary")]
		public bool IsRotary
		{
			get;
			set;
		}

		[Required]
		[Display(Name = "NeededPlaces")]
		public int NeededPlaces
		{
			get;
			set;
		}

		//See here for list of answers
		public int Result
		{
			get;
			set;
		}
	}

	public class Arg
	{
		public string places
		{
			get;
			set;
		}
	}
}

 
using System;
using System.ComponentModel.DataAnnotations;
​
namespace FindFreePlaceMvcApp
{
    public class ViewModel
    {
        [Required]
        [MinLength(10)]
        [MaxLength(100)]
        [Display(Name = "Places")]
        [RegularExpression(@"([tfTF]+)", ErrorMessage = "Invalid bool array")]
        public string Places
        {
            get;
            set;
        }
​
        [Required]
        [Display(Name = "IsRotary")]
        public bool IsRotary
        {
            get;
            set;

@model FindFreePlaceMvcApp.ViewModel
@{
	Layout = null;
}

<!DOCTYPE html>
<!-- template from http://getbootstrap.com/getting-started -->

<html lang="en">
	<head>
		<meta charset="utf-8">
		<meta http-equiv="X-UA-Compatible" content="IE=edge">
		<meta name="viewport" content="width=device-width, initial-scale=1">
		<title>Bootstrap 101 Template</title>

		<!-- CSS Includes -->
		<link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
		
		<style type="text/css">

			.field-validation-error {
				color: #ff0000;
			}

		</style>
	</head>
	
	<body>
		<div class="container">
			<div class="col-md-6 col-md-offset-3">
	
				@using (Html.BeginForm())
				{
					<div class="form-group">
						@Html.LabelFor(m => m.Places)
						@Html.TextBoxFor(model => model.Places, new {@class="form-control"}) 
						@Html.ValidationMessageFor(model => model.Places)
						@Html.LabelFor(m => m.IsRotary)
						@Html.CheckBoxFor(model => model.IsRotary, new {@class="form-control"}) 
						@Html.ValidationMessageFor(model => model.IsRotary)
						@Html.LabelFor(m => m.NeededPlaces)
						@Html.TextBoxFor(model => model.NeededPlaces, new {@class="form-control"}) 
						@Html.ValidationMessageFor(model => model.NeededPlaces)
					</div>
				
					<button type="button" class="btn btn-success submit">Ask</button>
				}
	
				<br/><br/>
				<div class="alert alert-warning fade">
					<strong><span class="alert-content"></span></strong>
				</div>
			</div>
		</div>

		<!-- JS includes -->
		<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
		<script src="//netdna.bootstrapcdn.com/bootstrap/3.1.1/js/bootstrap.min.js"></script>
	
		<script src="//ajax.aspnetcdn.com/ajax/jquery.validate/1.11.1/jquery.validate.min.js"></script>
		<script src="//ajax.aspnetcdn.com/ajax/mvc/4.0/jquery.validate.unobtrusive.min.js"></script>
		
		<script type="text/javascript">
		
			function openAlert(txt) {
				$('.alert-content').text(txt);
				$('.alert').addClass('in');
			}
		
			function closeAlert() {
				$('.alert').removeClass('in');
			}
		
			$(function(){
				var result = '@Model.Result';
				
				openAlert("result");
		
				$('#Question').change(closeAlert);
				$('#Question').keyup(closeAlert);
		
				$('.submit').click(function(){
					if($('form').valid()) {
					
						$.ajax({
							url: '@Url.RouteUrl(new{ action="GetAnswer", controller="Home"})',
							data: {	Places: $('#Places').val(), 
								   IsRotary: $('#IsRotary').is(':checked'), 
								   NeededPlaces: $('#NeededPlaces').val()
								  },
					
								type: 'POST',
								dataType: 'json',
								// contentType: "application/json; charset=utf-8",
			// processData: false,
								error: function(jqXHR, status, errorThrown) {
									openAlert(status + " " + errorThrown);
								},
								success: function(resp) {
								openAlert(resp);
						}});
			openAlert("valid");
					}
					else {
						closeAlert();
					}
				});
			
			});

		</script>
	</body>
</html>

        <script src="//ajax.aspnetcdn.com/ajax/jquery.validate/1.11.1/jquery.validate.min.js"></script>
 
@model FindFreePlaceMvcApp.ViewModel
@{
    Layout = null;
}
​
<!DOCTYPE html>
<!-- template from http://getbootstrap.com/getting-started -->
​
<html lang="en">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>Bootstrap 101 Template</title>
​
        <!-- CSS Includes -->
        <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
        
        <style type="text/css">
​
            .field-validation-error {
                color: #ff0000;
            }
​

using System;
using System.Web.Http;
using System.Web.Mvc;
using System.Collections.Generic;

class Solution
{
	static public int FindFreePlace(bool[] places, bool isRotary, int neededPlaces)
	{
		// Insert the code 
		int freeCount = 0;
		int freeStart = -1;
		int startCount = 0;
		for (int here = 0; here < places.Length; ++here)
		{
			if (!places[here])
			{
				if(freeStart == 0)
					startCount = freeCount;
				freeCount = 0;
				continue;
			}

			if (freeCount == 0)
			{
				freeStart = here;
			}

			freeCount++;
			if (freeCount == neededPlaces)
				return freeStart;
		}

		return isRotary && freeCount + startCount >= neededPlaces 
			? freeStart : -1;
	}
}

namespace FindFreePlaceMvcApp
{
	public class HomeController : Controller
	{
		[HttpGet]
		public ActionResult Index()
		{
			return View(new ViewModel());
		}

		[HttpPost]
		public JsonResult GetAnswer(ViewModel arg)
		{
			// string rep = arg.Places;
			// jsonData = Request.InputStream.Length.ToString();
			bool[] places = new bool[arg.Places.Length];
			int i = 0;
			foreach (char c in arg.Places)
			{
				places[i++] = (c == 't' || c == 'T');
			}
			

			return Json(Solution.FindFreePlace(places, arg.IsRotary, arg.NeededPlaces));
		}
	}
}

 
using System;
using System.Web.Http;
using System.Web.Mvc;
using System.Collections.Generic;
​
class Solution
{
    static public int FindFreePlace(bool[] places, bool isRotary, int neededPlaces)
    {
        // Insert the code 
        int freeCount = 0;
        int freeStart = -1;
        int startCount = 0;
        for (int here = 0; here < places.Length; ++here)
        {
            if (!places[here])
            {
                if(freeStart == 0)
                    startCount = freeCount;
                freeCount = 0;
                continue;
            }
​
            if (freeCount == 0)