“Count the number of space characters in a string.”

1. (4 pts) Using words provide a recursive description of this problem. Be sure to identify a base condition as well.
2. (6 pts) Write a recursive function called countSpaces that takes a String as a parameter and returns the number of space characters in it.

public static int f(int a, int b) {
   int remainder = a % b;
   if (remainder == 0)
      return b;
   else
      return f(b, remainder);
}

1. (4 pts) What value is returned by this method if invoked with ?
2. (2 pts) Is this method tail recursive, or not?

public class Customer
{
   private String email; // customer email address
   private int cablePackage;  // 1=basic; 2=supreme; 3=everything
   private boolean wantsPromotions; // false= don't send promotional emails

   public Customer(String email) {
      this.email= email;
      cablePackage= 1;
      wantsPromotions= true;
   }
   public void setCablePackage(int val) { cablePackage= val; }
   public int getCablePackage() { return cablePackage; }
   public double calcBill() {
      if (cablePackage == 1)
         return 19.99;
      else if (cablePackage == 2)
         return 39.99;
      else
         return 64.99;
   }
}

1. (4 pts) Some customers pay for Internet service in addition to their TV services. Create a new class called ICustomer that inherits from Customer and adds an integer attribute called speed that indicates the Mbps (10, 20, or 50) the customer has requested for their Internet service.

2. (6 pts) In the new ICustomer class create a constructor that accepts the email address of the customer and the speed of Internet service. It should invoke the constructor of it's super class.

3. (8 pts) In the ICustomer class override the calcBill method so that the monthly bill includes the amount for TV services and adds the following amount for Internet service: 10Mbps=$24.99, 20Mbps=$34.99, 50Mbps= $44.99. Then apply a 10% discount as a reward to customers for purchasing both services.

4. (4 pts) Draw a UML diagram depicting these two classes. When depicting attributes you should specify their type. When depicting methods you should specify their return type, name, and parameters.

1. (3 pts) Write code to declare an array of 10 customers.
2. (3 pts) In the first slot of the array create an ordinary (non-Internet) customer with an email address of your choice.
3. (3 pts) In the second slot of the array create an an Internet customer who has the fastest available service.
4. (3 pts) Modify the second customer's cable package to the most expensive package.
5. (3 pts) Display the expected bill for each customer.

Suppose the following class has been developed to represent the value and state of a given grid element:

[fontsize=\small]
class GridElement
{
   public int value;  // 0 if blank; -1 if bomb; -2 if border of the board;
                      // or 1-8 based on # of adjacent bombs
   public char state; // 'H' if hidden; 'V' if clicked/visible;
                      // 'M' if marked by user as a bomb
   public GridElement() { value= 0; state='H'; }
}

1. (4 pts) Create a class called Grid that is used to represent a minesweeper board. The board should be a two-dimensional array of GridElement objects. The class should also store the number of rows and columns in the board. Use the names board, rows, and cols for your attributes.

2. (8 pts) Write a method for the Grid class called countBombs that will look at an existing (initialized) board and return the number of bombs that exist.