Problem Solving Assignment 7

Due Monday, February 26 at 11:59pm PST

There is one problem in this PSA.

Notes:

• This IS a pair assignment. You MUST do the assignment with your partner.

• You must complete an interview with a Lab Tutor for this PSA. Interviews are individual (partly to ensure that one partner doesn't do all the work). See instructions here for more details.

• This work should be done in its own directory called 'psa7'. Instructions here.

• This assignment has sample solution code that you can run on ieng6. You won't be able to see the java code itself =) but you will be able to do tests to see what it does, and make sure yours does the same thing. YOUR CODE MUST DO THE EXACT SAME THING. EXACT!! Wording, spaces, everything. Instructions on how to run the sample solution code are here .

• Each file must have a header with the team members' names, logins, and PIDs. The header should also describe the program in 2-3 sentences.

This homework requires skills from Chapter 1 through Chapter 4.

Problem

Implement a class that will represent the odometer of a vehicle (the equipment that keeps track of fuel and mileage). You will use that class to develop an application that will help a traveller decide which car to rent between two different types (an offroad vehicle or a regular one). His goal is to travel from one city (starting position) to another (ending position) with the less possible expenses.

Introduction:

• The Odometer class should have two instance variables that represent:
  • the total amount of miles the car has traveled
  • the car's fuel efficiency, which is the quantity of miles per galon
• Also, the Odometer class should have the following public mutator methods:
  • void resetMileage(); , which resets the mileage of the vehicle to 0
  • void setFuelEfficiency(double); , which sets vehicle's fuel efficiency to the given value passed as a parameter
  • void addTripMiles(double); , which increases odometer's mileage by the given trip distance
• Finally, the Odometer class should have the following public access methods:
  • double getConsumedGallons(); , which gives the number of galons consumed since the last reset of the odometer
  • double getMileage(); , which gives the number of miles the vehicle has travelled since the last reset of the odometer
  • double getFuelEfficiency(); , which gives the fuel efficiency of the vehicle
• The traveller is equipped with a map and can choose between different paths. Each path is composed of road segments (e.g. the paths may have some road segments in common). There are some road segments that can be used effectively only with the offroad vehicle though; If the traveler choses the regular vehicle in such a segment, then there is a penalty in the that car's fuel efficiency: it is divided by a factor of 1.1 each time the car passes such a segment.
• Added 2/23/07: some clarifications: The regular's car efficiency is altered permanently, each time the car enters an "offroad segment", so the final efficiency is dependent on the number of offroad segments the car will go through. Also, ASSUME that if the car efficiency is changed, then this applies globaly to *ALL* road segments.. even on the ones that it has already passed.
• Vehicles have different fuel efficiency parameters at the beginning and those are available to the traveler, (apparently the offroad vehicle consumes more fuel quantity per mile).
• The program should read the cars' (initial) fuel efficiencies, as well as the each path road segments (in miles). In the end, it should output the best combination of car and path.
• Added 2/23/07: Assume the maximum number of fuel that can be consumed is 1000000 galons.

Details:

• Create your Odometer class. It must be put in a file called Odometer.java
• Your program should be in a file called TravelAdviser.java
• Create two Odometer objects, one for the offroad car, one for the regular car
• Ask the user how many paths he has in mind, and then ask for segments of each path as well as wherer that segment is "offroad" or not. Check the sample solution.
• In the end you should print:
  • the most economic car (offroad or regular) accompanied with...
  • the most economic path (1st? 3rd?)
  • the total distance the car will make
  • total amount of fuel in galons the car will consume

Hints:

• After you create the Odometer class, start creating the program, while testing the class' methods
• Remember that now you are using objects. Use as much as you can the class' public methods; code will get more simplified.

Details

Start by creating a directory (folder) in your ieng6 cs8fzz account (this is necessary for the bundle-psa7 script). After you log in, create a directory by typing the commands:

-bash-2.05b$ mkdir psa7

Go into that directory (like double clicking to open a folder) with the command:

-bash-2.05b$ cd psa7 

Note: you must name your directories (folders) and files as indicated in the problem descriptions for the turn in program to work.

In order to run the sample solution program you should invoke the following command:

-bash-2.05b$ runsample [classname]

In this assignment: "runsample TravelAdviser"

This assignment is worth 20 points.

General (4 pts):
• 1 Point: For proper formatting. Your code is properly and consistently indented.
• 1 Point: For documentation. You must write a 2-4 sentence description of the program (as a comment) that provides insight into what the program does and what it's useful for. In this header comment, you are also required to put the author names, author PIDs and author logins
• 2 points: Interview (done individually) see instructions here

  Odometer.java (7 pts):

• 1 point: Implement correctly the constructor
• 3 points: Implement correctly each of the three mutator methods (resetMileage, setFuelEfficiency, addTripMiles)
• 3 points: Implement correctly each of the three access methods (getConsumedGallons, getMileage, getFuelEfficiency)

  TravelAdviser.java (9 pts):

• 1 point: Correctly input all segments of all paths
• 1 point: Correctly creating the Odometer objects
• 3 points: Using all class methods (not instance variables!!)
• 2 points: Correctly output economic solution: car and path
• 2 points: Correctly output economic ditance and fuel consume

How to turn in your homework electronically

When you are ready to turn in your homework, run bundle-psa7 from your psa7 directory. The session should look like this:

-bash-2.05b$ cd ~/psa7
-bash-2.05b$ bundle-psa7
Good; all required files are present:

        Odometer.java
	Circle.java

Do you want to go ahead and turnin these files? [y/n]y
OK.  Proceeding.


Performing turnin of approx. XXXX bytes 
Copying to /home/linux/ieng6/cs8w/turnin.dest/cs8wzz.psa7
.
Done.
Total bytes written: XXXX 
Please check to be sure that's reasonable.
Turnin successful.

If you want to make changes after you've turned in your homework, make the changes and run bundle-psa7 again. The program will warn you that a "previously turned-in file exists" and ask if "you wish to over-write this existing file" (delete the old version and replace it with this new one). Respond in the affirmative by typing y and pressing the Enter key.

2 points of your grade on this assignment will come from an interview you will have with one of the tutors during Open Lab Hours. You have 48 weekday hours after the electronic turnin deadline to get your interview done. The deadline for the interview for PSA 7 is Monday, Feb 26, theoretically at midnight, but actually by the end of the last tutor hour scheduled. You get an interview by going into B260 during a scheduled tutor hour. Find the tutor, ask them if you can interview for PSA 7. If they have others who are waiting for interviews, your name will go on the end of the list of people waiting. Interviews take about 5 minutes each. It is your responsibility to go in early enough that you can get your interview completed. If everyone waits until the last hour on Wed, this will not work. The tutor will ask you to log in, change to the directory where your work is (psa7) and then to follow their directions. They will ask you to run your program to show that it works, open files in your favorite editor, and ask you questions about how your code works. Additionally, they may question you as to how you would (theoretically) make small changes to the program to have it do something slightly different. Learning to be able to explain your problem solving process and discuss code with another human being is a very important professional skill. We hope that this process will help you develop this skill.

Copying the assignment directory to partner's home directory

You can copy the psa7 directory and its files to your partner's home directory by:

bash% scp -r psa7 cs8wxx@ieng6.ucsd.edu:

(don't forget the colon at the end of the command) where cs8wxx is your partner's username. You must be in the parent directory of the psa7 directory. So, you if you are currently in the psa7 directory you should execute "cd ..". Similarly, if the psa7 direcory is in your home directory then you have to be in your home directory. If you aren't there just execute "cd ~" and you'll be there. Your partner is required to enter his password when you enter the scp command. To check if the copy worked, your partner must login and ckeck if the psa7 directory exists in his home directory and if the proper files are located in it. This can be done by executing: "ls ~/psa7". The files in the psa7 directory should be listed.

Redirecting the input and the output

You can redirect the input af a program by using the "<" symbol in the command line. Instead of reading the input from the standar input device (which is the keyboard):

bash% java MyProgram < sampleInput.txt

This command will redirect the input of the MyProgram program to the file sampleInput.txt. It will read the contents of the file as if they were given by pressing the buttons on keyboard. Similarly you can redirect the output af a program by using the ">" symbol in the command line. Instead of displaying the output on the standar output device (which is the computer monitor):

bash% java MyProgram > outFile.txt

This command will redirect the output of the MyProgram program to the file sampleInput.txt. It will write the output in the "outFile.txt" file (all contents of the will be erased if file exists, if it doesn't exist, it will be created) as if they would be printed on the computer screen (so, you won't get any output on the screen). You can combine both redirections. For example you may have an email.txt file with a sample email, and also you want the results of the scan to be put on the file output.txt. This can be done by:

bash% java MyProgram < email.txt > output.txt

Finding the differences between files

You can find the differences between two text files by using the diff command:

bash% diff filename1 filename2

The output will be the differences between the files. If there is no output at all that means that the files are identical.

Example: Testing the output of your program, can be completed in four steps, using the above tips.

Create a file with sample input (lets name it "input.txt" for your program (as if you would write it if the program was running)

Run your program and redirect the exit to a file: bash% java Statistics < input.txt > output1.txt

Run the provided program and redirect the exit to a second file: bash% runsample Statistics < input.txt > output2.txt

Check if there are differences between the two output files: bash% diff output1.txt output2.txt

Learning to use text editors

Vim

Run the command vimtutor, a separate program that will teach you to use Vim.

Emacs

Use the built-in tutorial by running emacs and, within the editor, typing CTRL-h t.

Pico

You can reach Pico's built-in help by typing CTRL-g. If you want further instruction, look at this Pico tutorial from NC State.