import java.awt.*;
import java.applet.*;
import java.util.Random;

/**
 * This class draws random points in and around a circle.
 */
public class Monte3 extends Applet
{
	private static Random randy;
	private int NUM_POINTS;
	private int SIZE;
	private Image offScreenImage;
	private Graphics offScreenGraphics;
	
	private int randomInRange(int low, int high)
	{
		return (Math.abs(randy.nextInt()) % (high-low+1)) + low;
	}
	
	private double distance(int x1, int y1, int x2, int y2)
	{
		return Math.sqrt(Math.pow(x1-x2, 2) + Math.pow(y1-y2, 2));	
	}
	
	public void init()
	{
		randy = new Random();
		NUM_POINTS = Integer.parseInt(getParameter("points"));
		Dimension dim = getSize();
		SIZE = Math.min(dim.width, dim.height);
	}
	
	public void paint(Graphics g) 
	{
		if (offScreenImage == null) {
			offScreenImage = createImage(SIZE, SIZE);
			offScreenGraphics = offScreenImage.getGraphics();
			
			offScreenGraphics.setColor(Color.red);
			g.setColor(Color.red);
			offScreenGraphics.fillOval(0, 0, SIZE, SIZE);
			g.fillOval(0, 0, SIZE, SIZE);
			for (int i = 0; i < NUM_POINTS; i++) {
				int x = randomInRange(0, SIZE);
				int y = randomInRange(0, SIZE);
				if (distance(x, y, SIZE/2, SIZE/2) < SIZE/2) {
					offScreenGraphics.setColor(Color.white);
					g.setColor(Color.white);
				}
				else {
					offScreenGraphics.setColor(Color.black);
					g.setColor(Color.black);
				}
				offScreenGraphics.drawLine(x, y, x, y);
				g.drawLine(x, y, x, y);
			}
		}
		else {
			g.drawImage(offScreenImage, 0, 0, null);
		}
	}
}