Игра пятнашки, как проверить где пустое поле для перемещения соседних кнопок - C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
 
namespace Fifteen
{
    public partial class Form1 : Form
    {
        int[,] field=new int[4,4];
        int[] mass=new int[16];
        Random myRand = new Random();
        Button[] ButtonArray = new Button[16];
        List<int> array =new List<int> { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0 };
        public Form1()
        {
            InitializeComponent();
            int x = 0;
            int y = 0;
            for (int i = 0; i < ButtonArray.Count(); i++)
            {
 
                ButtonArray[i] = new Button();
                int randomNumber = myRand.Next(array.Count);
                ButtonArray[i].Text = array[randomNumber].ToString();
                array.RemoveAt(randomNumber);
 
                switch (i)
                {
                    case 4: y = y + 40;
                        x = 0;
                        break;
                    case 8: y = y + 40;
                        x = 0;
                        break;
                    case 12: y = y + 40;
                        x = 0;
                        break;
                }
 
                    ButtonArray[i].SetBounds(x, y, 50, 40);
                x = x + 50;
                if (ButtonArray[i].Text == "0")
                    ButtonArray[i].Visible = false;
                this.Controls.Add(ButtonArray[i]);
                this.ButtonArray[i].Click +=new EventHandler(Button_Click);
               
            }
            
        }
 
        private void Button_Click(object sender, EventArgs e)
        {
            Button bt = (sender) as Button;
            Check();
            for (int i = 0; i < ButtonArray.Count(); i++)
            {
 
                if (ButtonArray[i].Text == "0")
                {
                 
                    Point pt = bt.Location;
                    bt.Location = ButtonArray[i].Location;
                    ButtonArray[i].Location = pt;
 
                }
            }
 
        }
 
    }
}