ээээ

using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private Point GetButtonCenter(Button button)
        {
            return new Point(
                    button.Location.X + button.Size.Width / 2,
                    button.Location.Y + button.Size.Height / 2
                );
        }

        private void DrawLinePoints(object sender, PaintEventArgs e)
        {
            if (currentPath == null || currentPath.Count < 2)
                return;

            Pen blackPen = new Pen(Color.DarkRed, 3);

            for (int i = 1; i < currentPath.Count; i++)
            {
                var point1 = GetButtonCenter(buttonsMap[currentPath[i - 1]]);
                var point2 = GetButtonCenter(buttonsMap[currentPath[i]]);

                e.Graphics.DrawLine(blackPen, point1, point2);
            }
        }

        private List<int> GetPath(int start, int end)
        {
            var arrayLenght = buttonsMap.Length;
            var weights = new int[arrayLenght, arrayLenght];
            var input = File.ReadAllText("nodes.txt").Split(' ', '\n');

            var currentStr = 0;
            Graph graph = new Graph(arrayLenght);

            for (var i = 0; i < arrayLenght; i++)
            {
                for (var j = 0; j < arrayLenght; j++, currentStr++)
                {
                    weights[i, j] = int.Parse(input[currentStr]);

                    if (weights[i, j] != 0)
                        graph.AddEdge(i, j, weights[i, j]);
                }
            }

            return Program.Dijkstra(graph, start, end);
        }

        private List<int> currentPath = new List<int>();
        private List<int> buttonsQueue = new List<int>();

        private void ButtonMap_Click(object sender, EventArgs e)
        {
            var button = sender as Button;
            var buttonIndex = (int)button.Tag;

            buttonsQueue.Add(buttonIndex);
            button.BackColor = Color.Gray;

            if (buttonsQueue.Count == 2)
            {
                currentPath = GetPath(buttonsQueue[0], buttonsQueue[1]);

                foreach (var index in currentPath)
                    buttonsMap[index].BackColor = Color.Gray;

                Refresh();
            }

            if (buttonsQueue.Count == 3)
            {
                foreach (var index in currentPath)
                    buttonsMap[index].BackColor = Color.FromKnownColor(KnownColor.ControlLight);

                buttonsQueue = new List<int>() { buttonIndex };
                currentPath = null;

                Refresh();
            }
        }
    }
}