CS 101X - Spring 2008

Jim Cohoon

Home | Documents | Homework | Slides |  People | Uploads
Activities | Code | Software | Email Log  | Grades

We learn best when we must invent -- Jean Piaget
Want what you do -- Jim Cohoo

   

Assignment XVII Due Thursday 04/24/08 by 1:00 AM

 

Assignment XVI Canceled

 
  • Develop a better setSequence() method for a strand.

Assignment XV
Due Friday 04/18/08 by 2:00 PM
  • From the activities section section for 04/16/08:
    • Complete Calculator.java
    • Complete CalculatorTester.java
  • Hand in a typed description of the constructors and methods that should be in class Course

Program Assignment XIV
Due Monday 04/07/08 by 2:00PM
  • Complete the factorial in Factorial.java.
  • Complete the Taylor expansion for e(x) in Taylor.java.
    • 1 + x/1! + x*x/2! + x*x*x/3! + ...
    • Because we do not want to go on forever, the second input to the your taylor method specifies the last term you are to consider (x raised to the nth power) / n!
    • Observer the jth term in the series can be obtained by multiplying the previous term by x and dividing by j

Program Assignment XIII
Due Monday 04/07/08 by 10:00PM
  • Complete the remaining checking methods in TicTacToe.java.
  • Algorithm for checking a vertical win starting at row r and column c of the board
    • If the position is empty, there cannot be a win.
    • If there is enough rows beyond r, there cannot be a win; that is, if r+k > number rows, then no win
    • Otherwise, the contents of the board in column c, rows r+1, r+2, ... r+k-1 need to be compared to the contents of row r and column c. If there is ever a mismatch, then there is no win. If there was no mismatch there is a win.

Program Assignment XII
Due Wednesday
03/26/08 by 2:00PM
  • Complete the incrementRed() task in StudentCode.java. To see this task work in photo manipulation also download ImageGUI.java and Library.java. When you execute StudentCode.java, it will use those files to run the display.
    • incrementRed(): Increases the amount of red in the pixel array by amount delta. If the new red value is in the interval 0 .. 255, then it is used to set the element. If instead, the new red value is negative, 0 is used as the new value. If instead the new red value is greater than 255, 255 is used as the new value for the array element.
  • In completing the incrementRed() task, the method Library.rgbtoInt() may be helpful. For example, the assignment

    • array[x][y] = Library.rgbToInt( newRed, g, b );

sets element array[x][y] to represent the color with levels newRed, g, and b respectively of red, green, and blue.

  • Extra credit: complete incrementBlue() and incrementGreen() to respectively alter the blue and green levels in the pixel array. The extra credit is only possible if incrementRed() is correct.

Program Assignment XI
Due Friday
03/21/08 by 2:00PM
  • Complete the copy(), flip(), and mirror() tasks in StudentCode.java. To see these tasks work in photo manipulation also downlown ImageGUI.java and Library.java. When you are execute StudentCode.java., it will use those files to run the display. There is nothing you need in those files to help perform tthe copy(), flip(), and mirror() tasks.
    • copy(): copies the elements of array original into the corresponding elements of array duplicate
    • flip:(): the elements of each row in array are reversed.
      • If the array was originally
        • 4 2 1 0
        • 3 7 5 4
        • 6 9 2 5
      • then it should end up as
        • 0 1 2 4
        • 4 5 7 3
        • 5 2 9 6
    • mirror(): the elements of each column in array are reversed.
      • If the array was originally
        • 4 2 1 0
        • 3 7 5 4
        • 6 9 2 5
      • then it should end up as
        • 6 9 2 5
        • 3 7 5 4
        • 4 2 1 0

Program Assignment X
Due Wednesday
03/19/08 by 5:00PM
  • Complete program MaximumCount.java. The program reports the number of times the maximum value occurs in an array.
  • Complete program IsSorted.java. The program reports whether a user-specified array has its elements in sorted order.

Program Assignment IX
Due Friday
03/14/08
by 5:00PM
  • Complete program KeyCount.java. The program counts the number of occurrences of a user-specified input value.

Program Assignment VIII
Due Wednesday
03/12/08 by 5:00PM
  • Complete program ArrayMaximum.java. The program determines the maximum array element value.
  • Complete program Negate.java. The program negates the values of an array

Program Assignment VII
Due Friday
02/29/08 by 5:00PM

Program Assignment
VI
Due Wednesday 02/27/08 by 10:00 PM

Programming
Assignment
V
Due Tuesday 02/12/08
by
10:00 PM

 
  • Complete program EVM.java from today's activities and submit it. The program should
    simulate the Earth and Venus circling the sun, and the moon circling the earth. Distances are specified within the program.

Programming
Assignment IV
Due Friday 02/8/08
by
10:00 PM
  • Complete program EV.java from today's activities and submit it. The program should
    simulate the Earth and Venus circling the sun.


 

Programming
Assignment III
Due Friday 02/1/08
by
5:00 PM

 
  • Complete program CarbonDater.java from today's activities and submit it. Remember function Math.log() calculates logarithms.
  • Develop and submit program AverageNumbers.java. The program should prompt its user for a list of numbers and then calculate and report the average. My suggestion in class was to modify and rename program SumNumbers.java from today's activities .

Programming
Assignment II
Due Wednesday 01/30/08
by
10:00 PM

Purpose

  • Demonstrate the ability to produce an interactive program.

Submissions

Summary

  • Complete console program MediaPlayerSizer.java so that it computes an estimate of the space needed by a media player to store a user-specified number of songs, minutes of video, and photos.

 

Problem -- sizing a media player

  • The program MemorySizer.java analyzed in class even when modified to accept the size of a music library does not meet most people's needs for sizing a media player -- the program only considers the the number of songs to be stored. People now also put photos and videos on their players. You are to create a better media player sizer -- a console program named MediaPlayerSizer.java.

    Program MediaPlayerSizer.java is to get four inputs from its user. They are

    • Desired number of songs,
    • Desired minutes of video,
    • Desired number of photos,
    • The rating resolution of their digital camera; that is, the maximum number of mega pixels used in capturing an image.

    The inputs are to be acquired in the listed order: songs, video, photos, and resolution. While this requirement may seem arbitrary, it greatly helps the people who are reading, testing, and grading the class submissions. Disregarding this requirement will cause a significant grading point loss.

Design details

  • The estimate for the needed size of a media player would be the sum of three amounts

.(number of giga bytes for songs + number of giga bytes for video
      + number of gigabytes for photos)

  • The number of giga bytes needed to store the songs is

(number of songs • gigabytes per song)

  • The number of giga bytes needed to store the video is

(minutes of video • gigabytes per video minute)

  • Because the camera resolution supplied by the user is in mega pixels, a scaling is required to  compute the giga byte photo requirements. Therefore, the number of giga pixels needed to store the photos is

(number of photos • mega pixel photo resolution / mega pixels per gigapixel)

As each pixel requires a byte of memory, the needed number of giga bytes is the number of giga pixels.

  • In estimating the media player size use the following assumptions:
    • The size of a song is expected to be on average 0.00471 gigabytes (this average was the one used by MemorySizer.java).
    • The size of a minute of video is expected to be 0.21666 gigabytes.
    • Your program should be user friendly.
      • It should start by displaying a message to the user.
      • It should give meaningful prompts to the user for the inputs.
      • Echo back the inputs so that the user sees how the program did its processing.

      For example, a run of my implementation of MediaPlayerSizer.java produced the following interchange (the blacken underscored text was user by the user).


       Welcome to media player calculator.  The calculator will ask four
       questions.  Based on your responses, a suggested minimal player
       size will be estimated.

       How many songs do you want to store: 3000
       How many minutes of video do you want to store: 180
       How many photos do you want to store: 1000
       What is the mega pixel resolution of your camera: 7.5

       A media player storing
          3000 songs
          180 minutes of video
         1000 7.5 photos
       needs at least 60.6288 GBs.
       

The algorithm and its implementation

  • Because this effort is your first attempt at implementing an interactive program, an algorithm is supplied to assist you in solving the problem. My process for developing the algorithm was a visualization process. I first considered how the program interactions should appear. I then decided what steps were needed to produce those interactions. I settled on the following
    1. Display an appropriate message to orient the user about the program.
    2. Set up an interface to the user for getting input.
    3. Determine what the user expects of the player
      • Prompt the user to supply the number of songs and get the user's response.
      • Prompt the user to supply the minutes of video and get the user's response.
      • Prompt the user to supply number of photos and get the user's response.
      • Prompt the user to supply the mega pixel resolution of  the camera and get the user's response.
    4. Specify constants needed for computing player size
      • Average number of giga bytes per song
      • Average number of giga bytes per minute of video
      • Number of mega pixels per giga pixel
    5. Calculate the player size
      • Determine the song needs
      • Determine the video needs
      • Determine the photo needs
      • Sum the three multimedia needs
    6. Display a summary of the requirements and the size estimate.

Testing your program

  • In general, a program is worthwhile as long as it is correct. So as part of the assignment you need to test your program. It is unreasonable to test your program with all possible inputs and compare its answers with the expected answers -- it would take too long. However, it is possible to come up with a small set of tests to provide confidence in its construction. So what tests make sense? One test would be to use mine from above. It gives you ability to test your program and compare it to know good results. So what other tests would be good. I believe three to five tests would do it.

Recommendations

  • Do not delay, the first interactive program is always hard to do.
  • Understand what is being asked and required of you before writing any code.
  • Download the provided program skeleton MediaPlayerSizer.java.
  • Add header comments to the program that identify your name, email id, section, and the program purpose.
  • Before adding any code to your method main() I would copy the six major steps listed above into the method main() and make them into comments to document the actions of the method main(); e.g.,

    // Display an appropriate message to orient the user about
    // the program.

  • Introduce white space to keep the steps visually separate.
  • Work on the six steps in order. Make sure the current step you are working is correct before preceding to the next step.
  • Use meaningful variable and constant names that follow Java style conventions.
  • Check the program's correctness by running test cases and hand checking program results with expected results.
  • Make sure the program has been cleaned up -- remove spurious output that you may have added when debugging the program.
  • Make sure the program is easy to read -- reasonable whitespace and comments.
  • Recheck the program's correctness by running test cases again to make sure cleaning up did not mess things up.

Grading

  • When graders examine your program and test methodology they will make their decision by considering:
    • Does the program header supply what is expected -- purpose, name, id, and section?
    • Is the program properly commented?
    • Is the use of whitespace appropriate?
    • Does the program display an appropriate legend?
    • Does the program display proper prompts for getting the user to provide correct responses?
    • Does the program make good use of Scanner for getting the responses?
    • Does the program define and consistently use appropriate constants?
    • Does the program define and appropriately initialize its variables.
    • Are the names of variables and constant reasonable and do they follow Java programming style.
    • Does the program compute the correct estimate?
    • Does the program display the expected summary in a reasonable manner?
    • Does your test set methodology make sense?
 

Programming Assignment
I
Due
Friday 01/25/08
By
 5:00 PM
  • Modify and submit program Ugly.java and introduce suitable whitespace to make the program reader (aesthetic) friendly. Do not change any of the code -- the program must still compile and perform the same actions.
    // Purpose: to display several eye idioms
    // Source: www.usingenglish.com
    public class Ugly{public static void main(String[]args){
    System.out.
    println("Bat an eyelid");System.out.println("Bedroom eyes")
    ;System.out.println("Better than a stick in the eye");
    System.out.println("Blink of an eye");System.out.println(
    "Bright-eyed and bushy-tailed");System.out.println(
    "Cry your eyes out");
    System.out.println("Discerning eye");System.out.println(
    "In the twinkling of an eye");System.out.println(
    "More than meets the eye");
    System.out.println(
    "Mud in your eye");System.out.println(
    "Not bat an eye");System.out.println(
    "Pull the wool over someone's eyes"
    );
    System.out.println("Scales fall from your eyes");
    System.out.println("See eye to eye");
    System.out.println("Sight for sore eyes");
    System.out.println("Stars in your eyes");
    System.out.println("Turn a blind eye");
    System.out.println("Twinkling of an eye");
    }}
  • Modify and submit program UhOhUhOhUhOh.java to correct its three syntax errors and one implementation error. The program is suppose to display Elbow grease is never messy.
    // Purpose: display Elbow grease is never messy
    // Author:
    // Email ID:

    public class UhohUhohUhoh {

        // main(): program starting point
        public static void main(String[] args) {
            System.out.println("Elbow grease is often messy')  
        }
    }
  • Modify and submit program UVA.java to display
UUUU    UUUU  VVVV       VVVV  AAAAAAAAAAAA
UUUU    UUUU  VVVV       VVVV  AAAAAAAAAAAA
UUUU    UUUU   VVVV     VVVV   AAAA    AAAA
UUUU    UUUU    VVVV   VVVV    AAAA    AAAA
UUUU    UUUU     VVV   VVV     AAAAAAAAAAAA
UUUU    UUUU      VVVVVVV      AAAA    AAAA
UUUUUUUUUUUU       VVVVV       AAAA    AAAA
UUUUUUUUUUUU        VVV        AAAA    AAAA
 

Exercise
Set II
Due
Wednesday 01/23/08
By
 Start of class

 
  • Read Wing's paper on computational thinking and turn in a one page, single-spaced printed copy of a paper providing discussion and reaction;

 

Exercise
Set I
Due
Wednesday 01/18/08
By
 Start of class
  • Watch the video the last lecture and turn in a one page, single-spaced printed copy of a paper discussing the talk and its motivational power. There will be bonus credit if you hand in your copy at the start of the first class.