CS302 Fall 2012 Exam 2 Solution

// Part I: Write a complete program 
import java.util.Scanner;
public class DairyDelivery {
  public static void main(String[] args) {

    final double MILK_PRICE      = 2.75;
    final double BOTTLE_DEPOSIT  = 1.50;
    final int MIN_ORDER = 3;
    final double DISC1 = 10.0;     // DISCOUNT LEVELS
    final double DISC2 = 20.0; 
    final double DELIVERY  = 2.5;  // $ 0- 9.99 is $2.50
    final double DELIVERY1 = 1.5;  // $10-19.99 is $1.50
    final double DELIVERY2 = 0;    // $20+      is $0.00
    Scanner stdin = new Scanner(System.in);
    int halfgals = -1, bottles = -1;

    // Get number of bottles ordered
    while ( halfgals < MIN_ORDER ) {
      System.out.print("Number of half gallons? ");
      halfgals = stdin.nextInt();
      if (halfgals < MIN_ORDER) {
        System.out.println(
          "Error! Please enter an int >= "+MIN_ORDER);
      }
    }
    // Get number of empty bottles returned
    while ( bottles < 0 ) {
      System.out.print("Number of bottles returned? ");
      bottles = stdin.nextInt();
      if ( bottles < 0 ) {
        System.out.println(
          "Error! Please enter an int >= 0");
      }
    }
    // Compute invoice items
    double milk     = halfgals * MILK_PRICE;
    double deposit  = halfgals * BOTTLE_DEPOSIT;
    double refund   = bottles  * BOTTLE_DEPOSIT;
    double delivery = 2.50;                         // delivery chg is $2.50
    if ( milk >= DISC2 )      delivery = DELIVERY2; // if >= 20, chg is FREE
    else if ( milk >= DISC1 ) delivery = DELIVERY1; // else if >= 10, chg is $1.50
    double ppg = (milk + delivery) / (halfgals / 2.0); // price per gallon
    System.out.println(
      "Milk Subtotal:           $" + milk + "\n" +
      "Bottle Deposit Charge: +  " + deposit + "\n" +
      "Bottle Return Refund:  -  " + refund + "\n" +
      "Delivery Charge:       +  " + delivery + "\n" + 
      "Total Bill:            = $" + (milk+deposit-refund+delivery) + "\n" +
      "Cost Per Gallon:       = $" + ppg + "/gal" );
  } // end main
  
} // end class


// Part II: #1 Write a code fragment that replaces Wisc. or Wis. with WI
    //assume city references a city, state and zip code
    // for example "Windsor, Wis. 53598"; 

    String WI = "WI ";
    String S = "Wis. ";
    if ( city.contains(S) )  {
      int i = city.indexOf(S);
      city  = city.substring(0,i) + WI + city.substring(i+S.length());
    }
    S = "Wisc. ";
    if ( city.contains(S) )  {
      int i = city.indexOf(S);
      city  = city.substring(0,i) + WI + city.substring(i+S.length());
    }

// Part II: #2 Complete the update(double t) of the Ship class.
public void update( double t ) {
  if ( ! destroyed ) {
    updatePosition(t);

    if ( getPosition().getY()-getRadius() <= 0 || 
         getPosition().getY()+getRadius() >= Config.GAME_HEIGHT-1 ) {
      setRotation( -getRotation() );
    }

    if ( getPosition().getX()-getRadius() <=0 || 
         getPosition().getX()+getRadius() >= Config.GAME_WIDTH-1 ) {
           destroy();
    }
  }
}

// Part III: Write an Instantiable Class
import java.util.Random;
public class ProblemGen {

  public static final int ADD = 0;
  public static final int SUB = 1;
  public static final int MUL = 2;
  public static final int DIV = 3;

  private final int MIN; // 
  private final int MAX; // 
  private final int OP;  // 

  private int op1, op2;     // the operands
  private String question;  // the problem
  private double answer;    // the answer

  private static Random rng = new Random();

  public ProblemGen (int low, int hi, int op) {
    MIN = low; MAX = hi; OP = op; 
    nextQuestion();
  }
  private void nextQuestion() {
    op1 = rng.nextInt(MAX-MIN+1)+MIN; // randomly pick each operand
    op2 = rng.nextInt(MAX-MIN+1)+MIN;
    // set question and answer fields
    char c = '?'; answer = 0; 
    if ( OP == ADD )      { c = '+'; answer = op1 + op2; } 
    else if ( OP == SUB ) { c = '-'; answer = op1 - op2; } 
    else if ( OP == MUL ) { c = '*'; answer = op1 * op2; } 
    else if ( OP == DIV ) { c = '/'; answer = op1 / (double)op2; } 
    question = op1 + " " + c + " " + op2 ;
  }

  public String getQuestion() { return question; }
  public String toString()    { return question + " = " + answer; } 

  public boolean isCorrect( double possible ) {
    double err = 0.001; // returns true if possible is close to answer
    return ( answer-err < possible && possible < answer+err );
  }


// Part IV: #1 Write a code fragment that finds players with most points
    // Assume: ArrayList<Player> team = new ArrayList<Player>();
    int mostPoints = 0;
    for ( int i = 0; i < team.size(); i++ ) {
      if ( team.get(i).getPoints() > mostPoints ) 
        mostPoints = team.get(i).getPoints();
    }
    for ( int i = 0; i < team.size(); i++ ) {
      if ( team.get(i).getPoints() == mostPoints ) 
        System.out.println( "Most points scored by " + team.get(i) );
    }

// Part IV: #2  Write a complete method that counts individuals

  public static int[] countIndividuals( int [][] world ) {
    int uninfected = 0;
    int recovered = 0;
    int other = 0;
    for ( int i = 0; i < world.length; i++ ) {
      for ( int j = 0; j < world[i].length; j++ ) {
        if ( world[i][j] == Config.UNINFECTED )
          uninifected++;
        else if ( world[i][j] == Config.RECOVERED ) 
          recovered++;
        else if ( world[i][j] != Config.EMPTY )
          other++;
      }
    }
    int [] counts = { uninfected, recovered, other };
    return counts;
  }