MODULE 8 - SHEET 1

public class ThreadIntro
 { public static void main(String[] args)
    { ThreadJack jack = new ThreadJack();
      ThreadJill jill = new ThreadJill();
      jack.start();
      jill.start();
    }
 }

class ThreadJack extends Thread
 { public void run()
    { for (int i=0; i<10; i++)
       { System.out.println("Jack " + i);
         try
	  { this.sleep(1000L);
          }
         catch(InterruptedException e)
	  {}
       }
    }
 }

class ThreadJill extends Thread
 { public void run()
    { for (int i=0; i<10; i++)
       { System.out.println("Jill " + i);
         try
	  { this.sleep(500L);
          }
         catch(InterruptedException e)
	  {}
       }
    }
 }

// This yields:
//
// Jack 0
// Jill 0
// Jill 1
// Jack 1
// Jill 2
// Jill 3
// Jack 2
// Jill 4
// Jill 5
// Jack 3
// Jill 6
// Jill 7
// Jack 4
// Jill 8
// Jill 9
// Jack 5
// Jack 6
// Jack 7
// Jack 8
// Jack 9



        MODULE 8 - SHEET 2



public class BoxConcluded
 { public static void main(String[] args) throws InterruptedException
    { Square jack = new Square(6);
      System.out.println("Details of jack...\n" + jack.toString());
      Square jill = new Square(5);
      System.out.println("Details of jill...\n" + jill);
      System.out.println("Number of Squares: " + Square.total + "\n");
      jack = jill;
      jill = null;
      Thread.sleep(1000L);
      System.out.println("Number of Squares: " + Square.total + "\n");
      System.out.println("Details of jack...\n" + jack);
    }
 }

class Square
 { public static int total = 0;        // record the number of Squares...

   private int edge;

   public Square(int e)
    { this.edge = e;
      this.total++;                    // ...by incrementing total.
    }

   public int area()
    { return this.edge*this.edge;
    }

   public String toString()
    { return "Square: Edge = " + this.edge + "\n" +
             "        Area = " + this.area() + "\n";
    }

   public void finalize()
    { this.total--;
    }
 }

// This yields:
//
// Details of jack...
// Square: Edge = 6
//         Area = 36
// 
// Details of jill...
// Square: Edge = 5
//         Area = 25
//
// Number of Squares: 2
//
// Number of Squares: 1
//
// Details of jack...
// Square: Edge = 5
//         Area = 25



      MODULE 8 - SHEET 3



public class ReverseList
 { public static void main(String[] args)
    { Link start = new Link(16);
      start.put(8);
      start.put(4);
      start.put(64);
      start.put(32);
      System.out.println("List elements:  " + start);
      System.out.println("Element sum:    " + start.sum());
      Link rev = start.reverse();
      System.out.println("List elements:  " + rev);
      System.out.println("Element sum:    " + rev.sum());
    }
 }

class Link
 { private int val;
   private Link next;

   public Link(int n)
    { this.val = n;
      this.next = null;
    }

   public void put(int k)
    { if (this.next == null)
         this.next = new Link(k);
      else
         this.next.put(k);
    }

   public Link reverse()
    { if (this.next == null)
         return this;
      else
       { Link temp = this.next.reverse();
         temp.put(this.val);
         return temp;
       }
    }

   public String toString()
    { return this.val + (this.next == null ? "" : " " + this.next.toString());
    }

   public int sum()
    { return this.val + (this.next == null ? 0 : this.next.sum());
    }
 }



      MODULE 8 - SHEET 4



public class TreeSort
 { public static void main(String[] args)
    { Node tree = new Node(16);
      tree.put(8);
      tree.put(4);
      tree.put(64);
      tree.put(32);
      System.out.println("Tree elements:  " + tree);
      System.out.println("Element sum:    " + tree.sum());
    }
 }

class Node
 { private Node left;
   private int val;
   private Node right;

   public Node(int n)
    { this.left = null;
      this.val = n;
      this.right = null;
    }

   public void put(int k)
    { if (k < this.val)
         if (this.left == null)
            this.left = new Node(k);
         else
            this.left.put(k);
      else
         if (this.right == null)
            this.right = new Node(k);
         else
            this.right.put(k);
    }

   public String toString()
    { String s = ((this.left != null) ? this.left.toString() : "") +
                 this.val + " " +
                 ((this.right != null) ? this.right.toString() : "");
      return s;
    }

   public int sum()
    { int s = ((this.left != null) ? this.left.sum() : 0) +
              this.val +
	      ((this.right != null) ? this.right.sum() : 0);
      return s;
    }
 }



      MODULE 8 - SHEET 5



import java.io.DataInputStream;
import java.io.EOFException;
import java.io.IOException;

public class WordCount
 { private static final DataInputStream DIS = new DataInputStream(System.in);
   private static int count=0;

   public static void main(String [] args)
    { try
       { while (true)
          { String s = readWord();
	    count++;
          }
       }
      catch(EOFException e)
       { System.out.println("Total number of words: " + count);
       }
      catch(IOException e)
       { System.out.println("IOException Encountered");
       }
    }

   private static String readWord() throws EOFException, IOException
    { char ch;
      String s="";
      do
       { ch = (char)DIS.readByte();
       } while (ch==' ' || ch=='\t' || ch=='\n');
      do
       { s += ch;
         ch = (char)DIS.readByte();
       } while (ch!=' ' && ch!='\t' && ch!='\n');
      return s;
    }
 }

// Example run:
//
// $ javac WordCount.java
// The quick
// brown fox
// jumps over
// the lazy dog.
// ^d
//
// Total number of words: 9



      MODULE 8 - SHEET 6



public class CroquetA
 { private static int count=0;
   private static int[] plan = new int[28];
   private static boolean[] alreadyPlayed = new boolean[193];
   private static final int p1 = 1, p2 = 2, p3 = 4, p4 =  8,
                            p5 =16, p6 =32, p7 =64, p8 =128;
   private static final int maxgame = 28;

   public static void main(String[] args)
    { for (int i=0; i<=192; i++)
         alreadyPlayed[i] = false;
      tryit(0);
      System.out.println("There are " + count + " solutions");
    }

   private static void tryit(int game)
    { if (game == maxgame)
       { count++;
         printOut();
         System.exit(0);    //  Abort after printing first solution
         return;
       }
      int imposs = 0;
      for (int i = game & 0x1C; i<game; i++)
         imposs |= plan[i];
      int poss = ~imposs & 0xFF;
      int[] player = new int[8];
      int k = -1;
      while (poss!=0)
       { player[++k] = poss & -poss;
         poss &= ~player[k];
       }
      for (int i=0; i<k; i++)
         for (int j=i+1; j<=k; j++)
          { int pi = player[i];
            int pj = player[j];
            int pair = pi | pj;
            if (!(alreadyPlayed[pair]))
             { plan[game] = pair;
               alreadyPlayed[pair] = true;
               tryit(game+1);
               alreadyPlayed[pair] = false;
             }
          }
    }

   private static void printOut()
    { for (int lawn=0; lawn<4; lawn++)
       { for (int game=lawn; game<maxgame; game += 4)
            System.out.print(match(plan[game]) + "  ");
         System.out.println();
       }
    }

   private static String match(int pair)
    { String s = "";
      for (int p = pair & -pair; pair != 0; p = pair & -pair)
       { switch(p)
          { case p1:  s += 1;  break;
            case p2:  s += 2;  break;
            case p3:  s += 3;  break;
            case p4:  s += 4;  break;
            case p5:  s += 5;  break;
            case p6:  s += 6;  break;
            case p7:  s += 7;  break;
            case p8:  s += 8;
          }
         pair &= ~p;
       }
      return s;
    }
 }