//RandomWalk.java
import java.awt.Graphics;
import java.awt.Color;
import javax.swing.*;

public class RandomWalk extends JApplet {
    
    int lines;
    
    public void init() {
	String input;
	
	input = JOptionPane.showInputDialog("Enter # of steps to take");
	
	lines = Integer.parseInt(input);
    }

   public void paint( Graphics g )
   {
       int x1, y1, x2, y2, x, y;
       int xCenter=400;
       int yCenter=300;
		double totalDist=0, avgDist=0, dist;
		int scale=5;
       super.paint( g );

       //assumes screen area is 800x600
       x1 = x2 = xCenter;   //start in center
       y1 = y2 = yCenter;
       g.setColor(Color.RED);
       g.fillRect(x1-3,y1-3,5,5);
       g.setColor(Color.BLACK);       
	for (int i=1; i<=lines; i++) {
		switch ((int)(Math.random()*4)) {
	    case 0:  //up
	    	y2 = y1 - scale;
	    	break;
	    case 1:  //down
	    	y2 = y1 + scale;
	    	break;
	    case 2:  //left
	    	x2 = x1 - scale;
	    	break;
	    case 3:  //left
	    	x2 = x1 + scale;
	    	break;
	    }
	   
	   g.drawLine(x1,y1,x2,y2);
	   
	   x1 = x2;
	   y1 = y2;
	   
	   x = (x2 - xCenter) / scale;
	   y = (y2 - yCenter) / scale;
	   dist = Math.sqrt(x*x+y*y);
	   totalDist += dist;
	   avgDist = totalDist / i;
	   
	   showStatus("distance from origin: " + dist + "  Average distance: " + avgDist);
   
    }
   }
}