CompSci 6 Fall 2009 Test 2 solutions
(many have multiple solutions)

Problem 1

// PART A

 public ArrayList<Integer> findPositionOfAllOccurences(String dna, String reactant)
 {
    ArrayList<Integer> positions = new ArrayList<Integer>();
    int pos = dna.indexOf(reactant);
    while (pos >=0)
    {
       positions.add(pos);
       pos = dna.indexOf(reactant, pos+1);
     }
     return positions;
 }

public ArrayList<Integer> findPositionOfAllOccurences(String dna, String nuc)
{
    ArrayList<Integer> positions = new ArrayList<Integer>();
    for (int k=0; k < dna.length() - nuc.length(); k++) 
        if (nuc.equals(dna.substring(k, k + nuc.length())
            positions.add(k);
    return positions;
}

// PART B
 public String createOneFragment (String dna, int lastPosition)
 {
    String returnString = "";;
    String partial = dna.substring(0,lastPosition+1);
    for (char ch: partial.toCharArray())
    {
       String str = ch + "";
       returnString += complement(str);
     }
    return returnString;
 }


public String createOneFragment (String dna, int lastPosition)
{
    String result = "";
    for (int k=0; k <= lastPosition; k++) 
        result += complement(dna.substring(k,k+1));
    return result;
}

// PART C
 public  String [] generateFragments(String dna, String reactant, int number)
 {
    String [] fragments = new String[number];
    Random rgen = new Random();
    ArrayList<Integer> positions = findPositionOfAllOccurences(dna, complement(reactant));
    for (int k=0; k<number; k++)
    {
       int rand = rgen.nextInt(positions.size());
       fragments[k] = createOneFragment(dna,positions.get(rand));
    }
    return fragments;
 }
 
 

Problem 2
// PART A

public  Club(String name, String members)
{
    myName = name;
    String[] memList = members.split(":");
    myMembers = new TreeSet<String>();
    for (String name: memList)
        myMembers.add(name);
}

// PART B
public  DookClubs (Scanner input)
{
    myClubs = new ArrayList<Club>();
    while (input.hasNext())
        myClubs.add(new Club(input.nextLine(), input.nextLine()));
}

// PART C
public ArrayList<String> allMembers ()
{
  ArrayList<String> members = new ArrayList<String>();
  TreeSet<String> membersSetform = new TreeSet<String>();

  for (Club c: myClubs)
  {
      membersSetform.addAll(c.myMembers());
  }

  for (String str: membersSetform)
  {
      members.addAll(str);
  } 
  return members;
}

public ArrayList<String> allMembers () {
    ArrayList<String> members = new ArrayList<String>();
    for (Club c: myClubs)
      for (String name: c.getMembers())
        if (!members.contains(name))
          members.add(name);
    return members;
}

// PART D 
public ArrayList<String> peopleNotInClubs (ArrayList<String> students)
{
  ArrayList<String> peopleNotIn = new ArrayList<String>();
  TreeList<String> peopleIn = new TreeSet();
  peopleIn.addAll(allMembers());

  for (String str: students)
  {
      if (peopleIn.contains(str))
       peopleNotIn.add(str);
  }
  return peopleNotIn;
}

public ArrayList<String> peopleNotInClubs (ArrayList<String> students)
{
  TreeSet<String> peopleNotIn = new TreeSet();
  peopleNotIn.addAll(students);
  peopleNotIn.removeAll(allMembers());

  return new ArrayList<String>(peopleNotIn);
}

Problem 3

// PART A
public class LumComparator implements Comparator<Color>
{
    // Computes the luminance of c where luminance is defined as
    // 0.3R + 0.59G + 0.11B
    private int luminance(Color c)
    {
      return (int) (0.3*c.getRed() + 0.59*c.getGreen() + 0.11*c.getBlue());
    }

    // returns:
    //  < 0 if the luminance of c1 is less than c2
    //   0  if the luminance of c1 is equal to c2
    //  > 0 if the luminance  of c1 is greater than c2
    public int compare (Color c1, Color c2)
    {
      return luminance(c1) - luminance(c2);
    }   

// PART B

public class Student extends Command
{
    public Student ()
    {
        super("Sort Colors");
    }


   public void execute (Pixmap target)
    {
        Dimension size = target.getSize();
        AverageComparator comp = new AverageComparator();
        for (int j =0; j < size.width; j += 1)
        {
            // Add col to list
            ArrayList<Color> col = new ArrayList<Color>();
            for (int i=0; i < size.height; i+= 1)
                col.add(target.getColor(i, j));
            // sort list by luminance
            Collections.sort(col, comp);
            // Copy row back to target
            for (int i=0; i < size.height; i+= 1)
                target.setColor(i,j, col.get(i));                    
        }   
    }
}