private void button_Solve_Click(object sender, EventArgs e)
{
var timer = Stopwatch.StartNew();
SudokuSolver sudokuSolver = new SudokuSolver(Sudoku);
sudokuSolver.SolveSudoku();
var log = sudokuSolver.Log;
Heatmap = log.Heatmap;
textBox_Log.Text = log.LogText;
Text = timer.ElapsedMilliseconds + " ms";
pictureBox1.Refresh();
}