Computer Science 15-100 (Lecture 18), Spring 2009
Homework 0 (Pass/Fail)
Due:  Thu 15-Jan-2009 at 11:59pm (email copy) and at Friday's class/recitation (identical physical copy)
(no late submissions accepted).

Read these instructions first!

• This homework is Pass/Fail.  To pass, you must get a passing mark (60% or higher) on each of the three questions.  Passing marks will not be factored into your semester grade, but failing marks will count as a 0 in your homework average.
   
• Be sure to include your name, your Andrew ID, and your section clearly on the top of each file in your assignment.
   
• Also include a timesheet logging all the time you spent on the assignment.
  While this is required, you will not be graded on your number of hours, but this information will be helpful to the course staff.  You can include the timesheet in the header of a Java file or in its own text file (timesheet.txt).  It would be most helpful if you indicate roughly which problems you were working on at various times (so we can identify if there are any issues with time demands of these questions).
   
• For non-programming problems:
  • Place all your solutions to the non-programming problems in a single file named Hw0 (with whatever extension is appropriate for the format you choose, such as Hw0.txt or Hw0.html, etc).  You must use one of these file formats: plain text (txt), or RTF, or HTML, or Word (doc, not docx), or PDF.  No other file formats will be accepted.
  • Show your work.  Correct answers without supporting calculations will not receive full credit.
     
• For programming problems:
  • Place each solution in its own file named exactly as given below, and with a class name that exactly matches the file name.  So if the file name is Hw0Foo.java, the main class in that file must be Hw0Foo.
  • Try to use well-named variables, proper indenting, reasonable commenting, etc.
  • Note:  You may not use Java concepts we have not yet covered, including loops (do/while/for), conditionals ("if" statements or tertiary operators (?:)), arrays, or methods from any classes in java.util.* (besides Scanner or others we explicitly use) to solve these problems (which isn't a problem for most of you, seeing as we have not yet covered these!).  While they may be helpful, every problem here is solvable without them, and they are not permitted for now.
     
• What to submit
  • Create a submission directory like this:  "koz-hw0"  (replace "koz" with your andrew id)
  • Place all the files you are submitting in that directory, zip that directory, and submit the zipped directory
     
• How to submit
  • Send an email with the zipped submission directory as an attachment to your CA by the submission deadline.  Do not miss the deadline, even by one minute!  Email problems are not a valid excuse for late submissions.
  • It is recommended that you "cc" yourself in that email, too, just to confirm that you properly sent the email.
     
• Note:
  • Improper submissions will be penalized up to 10 points and may be rejected.
  • Late submissions will be rejected.

1. Mystery Code
2. Triangle Area
3. Flag of Belgium

1. Mystery Code
   In the written portion of your submission, answer this question:  under what conditions in general will the following program output zero?

   import java.util.Scanner;
   class MyCode {
     public static void main(String[] args) {
       Scanner scanner = new Scanner(System.in);
       System.out.print("Enter an integer: ");
       int x = scanner.nextInt();
       System.out.print("Enter another integer: ");
       int y = scanner.nextInt();
   
       // Hint:  x/y is INTEGER division, where the remainder is ignored!
       int mystery = (x/y) + (y/x) - 2;
       System.out.println(mystery);
     }
   }

2. Triangle Area
   In the file Hw0TriangleArea.java, write a program that reads in the base and height of a triangle and prints out its area (where the area of a triangle is one half the product of its base and height).  You should use integer division (so the remainder will be ignored).  While you must use good prompts and meaningful output, you do not have to worry about illegal inputs (such as a non-positive or non-integer base or height).
    
3. Flag of Belgium
   In the file Hw0FlagOfBelgium.java, write a program that displays the flag of Belgium:
     (larger image with details)
   
   Note: This flag image is from the very informational CIA World Factbook, which includes a flags-of-the-world page. 
   
   Your program should paint three filled rectangles, and should use built-in colors (so the colors might not match exactly, but they will be close).  Also, your flag may not be fixed-sized, but rather must entirely fill the window, even when the window is resized.  While the window's size may change, you may assume the window will be roughly "flag-shaped" -- you will not be graded on how your flag appears in, say, a tall thin window (which is not at all "flag-shaped"). 

Carpe diem!