求教：输入小球的行和列数就能画出由七种不同颜色球组成的图

        Color[] colors = new Color[] { Color.Red, Color.Orange, Color.Yellow, Color.Green, Color.Cyan, Color.Blue, Color.Pink };

        private void pictureBox1_Paint(object sender, PaintEventArgs e)

        {

            DrawCircle(e.Graphics, 5, 5);

        }

        private void DrawCircle(Graphics g, int row, int col)

        {

            Random random = new Random();

            int r = 10;

            for (int i = 0; i < row; i++)

            {

                for (int j = 0; j < col; j++)

                {

                    Rectangle rect = new Rectangle(j * r * 2, i * r * 2, 2 * r, 2 * r);

                    g.FillEllipse(new SolidBrush(colors[random.Next(7)]), rect);

                }

            }

        }