/** Copyright Henry Bottomley February 2002*/

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.lang.Math;
import java.math.BigInteger;


public class magicapplet extends Applet
 implements ActionListener
    {TextField box0, messagebox;
     int maxx;
             
     public void init()
         {
         box0 = new TextField(4); 
         add (box0); 
         Button calculate = new Button("Calculate magic series");
         calculate.addActionListener(this);
         add (calculate);
         messagebox = new TextField(50); 
         add (messagebox);
         }    
                 
     public void actionPerformed(ActionEvent event)
        {String arg=event.getActionCommand();
                         
        if (arg=="Calculate magic series")
            {
            maxx=Integer.parseInt(box0.getText().trim());
            int maxz=maxx*(maxx-1);
            int maxy=maxx*maxx*(maxx-1)/2;
            int numx=1;
            BigInteger rArray[][] = new BigInteger[maxx+1][maxy+1];  // this is large and growing and a potential memory problem
            for (int x=0; x<=maxx; x++)
                {for (int y=maxy; y>=0; y--)
                     {rArray[x][y]=BigInteger.valueOf(0l);   //start with all zero, except ... 
                     }
                }        
            rArray[0][0]=BigInteger.valueOf(1l);             //... except for a single one. 
            for (int z=0; z<=maxz; z++) 
                {for (int x=1; x<=maxx; x++)        //Need to increase to use previous values
                    {for (int y=maxy; y>=0; y--)    //Need to decrease to use previous values
                         {if (y>=x)                                    
                             {rArray[x][y]=rArray[x-1][y].add(rArray[x][y-x]);  //the recurrence: rArray[x-1][y] is new while rArray[x][y-x] is old 
                             }
                          else
                             {rArray[x][y]=rArray[x-1][y];  // rArray[x][y-x] does not exist if x>y
                             }
                         }
                    }
                if (numx*(numx-1)<=z)
                    {messagebox.setText(Integer.toString(numx) + "    " + rArray[numx][numx*numx*(numx-1)/2].toString());
                     numx++;
                    }    // end of if/messagebox 
                }        // end of z loop 
            }            // end of calculate magic series
        }                // end of actionPerormed
    }                    // end of class magicapplet