CSCI 1100 | Computer Science 1

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CSCI 1100 | Computer Science 1
Fall 2016
Homework 1: Calculations and Strings
Overview
This homework, worth 75 points total toward your overall homework grade, is due Thursday,
September 15, 2016 at 11:59:59 pm. The three equally-weight parts should each be submitted
separately. All parts should be submitted by the deadline or your program will be considered late.
General Comments: Read This Before Starting the Homework
Welcome to CS-1 homeworks. We are starting this assignment by outlining the course homework
policies. These will not be repeated so please read this carefully and refer back to it for future
assignments.
Submission of homeworks: test rst, but you can submit many times
As you learned in Lab 1, all homework will be submitted electronically through Submitty, the
Department of Computer Science homework submission and auto-grading server. This link is also
available on the course website. The homework submission server for a particular assignment will
typically be available no later than the Monday of the week the homework is due. So, you can
expect that for this homework, you should be able to submit by Monday, September 12, 2016,
perhaps sooner.
Make a habit of testing your program by running it using the Wing IDE. First, make sure that it
can run. Then, go through the logic to make sure that it is correct. Learning to test your code
is a big part of learning to program. Use Submitty, which can get slow near the deadline, for
submitting and nal changes rather than for testing. You will not be penalized for submitting a
program multiple times, but you are generally graded on the last solution you submit. Note that
the time you submit the last version determines whether a homework is late or not.
How will you be graded?
ˆ Program correctness will be the most important determinant of your grade. In some cases,
especially later in the semester, we will test your code with many di erent inputs, not just
the ones we provide as sample test cases in the homework description.
ˆ Small di erences in output spacing will cause small losses of points. While we care mostly
about correct logic, making sure the output matches the sample output exactly teaches you
to use the print function and strings e ectively.
ˆ In addition to looking at output, we will also read your code. Make sure your program is
well-written and has clear, correct program logic. Test it yourself with additional test cases,
not only the ones we give you. You may lose points even if you match all test cases but your
logic is unclear or incorrect.
ˆ We will look at programming style including the organization of your code, the written
comments describing the purpose of your code, the names of variables, the use of functions,
etc. This will be emphasized increasingly as we progress through the semester. It is important
to develop good habits even when writing relatively short programs.
ˆ Remember that generally the last version you submitted is the one that will be graded. You
can use Submitty to make a past submission the active one if you want us to grade that
one instead, but you need to specify this explicitly on the server. This must be done by the
submission deadline. It is your responsibility to manage it.
ˆ We often receive the question, can I use a programming construct that we have not
learned yet? While you may not lose points for doing so | unless we give you an explicit
warning | we strongly urge you not to. We design homeworks to speci cally target the
concepts we are learning right now. Hence, while there may be more advanced methods to
solve a problem, if you feel you need to use them you are not properly learning and applying
the concepts we are teaching.
Late homework policy
When a homework has multiple parts, the submission time is the time that the last part is sub-
mitted. For example, if you submit parts 1 and 2 three days before the due date and part 3 one
hour after the submission deadline, you will have used up one late day. Reread the late homework
policy in the syllabus. You have a total of three full or part days you can use for late homeworks in
the whole semester and up to two days can be used for a single homewor, assuming you have them
available. It is highly recommended that you save these for later homeworks that will be harder
and longer.
Wing IDE vs. Homework Submission server
On rare occasions when the homework submission server runs your code it will produce di erent
output than the Wing IDE does, even though both are using Python 3.5.2. In such cases pay
careful attention to the server’s output and try to gure out what happened. Usually you’ve done
something wrong in the way you wrote, submitted or executed your program. If you can’t x the
problem, check the Piazza site for a relevant discussion. Only after checking should you post a
Piazza question (and remember do not post your code!). This is also a good topic for help during
oce hours.
Input format for homeworks in this class
Your program must read the same number of inputs as are required according to the given problem.
For example, if we tell you to read a name rst and an email address next, that means your program
must have two input statements. If it does not, you will get an error like:
EOFError: EOF when reading a line
This means either you are trying to read too many or too few inputs. Read the problem speci cation
carefully.
In all homeworks, we will use a convention speci c to CS-1. If we ask you to read an input, then
after you read it you must immediately print that input. For example, the following is the correct
method to input the name string and the email address string:
name = input(‘Enter a name ==> ‘)
print(name)
email = input(‘Enter an email ==> ‘)
print(email)
The above program will produce a di erent output in Wing IDE and on Submitty, as shown below:
Enter a name ==> Rensselaer
Rensselaer
Enter an email ==> rpiinfo@rpi.edu
rpiinfo@rpi.edu
Enter a name ==> Rensselaer
Enter an email ==> rpiinfo@rpi.edu
Wing IDE output Homework submission output
(what you see on your computer) (what you see on submission server)
If you forgot to add the print function calls, you would actually see something like this in the
submission server which will be considered incorrect output:
Please enter a name==> Please enter your email==>
The di erence | and this is not really important for actually completing Homework 1 | is that
for each part of the homework, we place all the input into a le and do what’s called \running
from the command-line.” In the above example, we are using an input le (let’s assume it is called
input.txt) that contains the two strings Rensselaer and rpiinfo@rpi.edu on two lines.
When a program is run from a command shell, we use a command-line of the form:
python part1.py < input.txt
Unfortunately, the free version of the WingIDE that we have been using in class does not allow
us to specify this input. But, you can do the command-line form on Mac/Linux with a Terminal
window, and on Windows using Linux-derived Cygwin tools. If you want to learn how, you can
ask us during oce hours. Anyway, here is the bottom line:
Anytime you read input, just print it immediately afterwards to match the expected output.
The Actual Homework Description
With all of that as a backdrop, here is the actual homework assignment, in three parts.
Part 1: Astronomical Calculations
Jupiter, the largest planet in our solar system, has a diameter of 88,846 miles and its average
distance from the Sun is about 483,632,000 miles. These are big numbers and as such they are a
bit hard to understand intuitively. One way to appreciate them is to compare them to the values
for Earth, which has a diameter of 7,926 miles and a distance from the Sun of about 92,957,100
miles. The size can also be compared to the Sun, which has an average diameter of about 864,938
miles. Use 186,000 miles per second as the speed of light.
Write a Python program to calculate and output
1. the ratio of the Sun’s radius to Jupiter’s,
2. the ratio of the Sun’s radius to Earth’s,
3. the ratio of Jupiter’s radius to Earth’s,
4. the ratio of Jupiter’s distance from the Sun to the Earth’s distance from the Sun,
5. the ratio of Jupiter’s volume to that of the Earth (assuming both are spheres),
6. the time in minutes it takes light to travel from the Sun to Earth (use 186; 000 miles per
second as the speed of light), and
7. the time in minutes it takes light to travel from the Sun to Jupiter.
Your output must match
Sun-to-Jupiter radius ratio: <number>
Sun-to-Earth radius ratio: <number>
Jupiter-to-Earth radius ratio: <number>
Jupiter-to-Earth Sun distance ratio: <number>
Sun-to-Jupiter volume ratio: <number>
Sun-to-Earth volume ratio: <number>
Jupiter-to-Earth volume ratio: <number>
Sun to Earth light travel time in minutes: <number>
Sun to Jupiter light travel time in minutes: <number>
where in each case <number> is replaced by the oating point value your program calculates. You
must use the value 3.14159 for  or your output will di er from ours. (We will see very soon how
to get more accurate values of .)
Your program must have the ve distances and diameter values typed into the code each exactly
once and then use variables after that. This would make it easy to change if, for example, we
decided to use the values for Saturn instead. It would be even better if a string variable stored the
name for Jupiter and then this name were used in the print statements.
Upload your Python program le to Submitty as Part 1 of HW 1.
Part 2: Speed Calculations
Many exercise apps record both the time and the distance a user covers while walking, running,
biking or swimming. Some users of the apps want to know their average pace in minutes and
seconds per mile, while others want to know their average speed in miles per hour. For example,
if I run 6.3 miles in 53 minutes and 30 seconds, my average pace is 8 minutes and 29 seconds per
mile and my average speed is 7.07 miles per hour.
Your job in Part 2 of this homework is to write a program that asks the user for the minutes,
seconds and miles from an exercise event and outputs both the average pace and the average speed.
Here is an example showing the expected output of your program:
Minutes ==> 53
Seconds ==> 30
Miles ==> 6.3
Pace is 8 minutes and 29 seconds per mile.
Speed is 7.065420560747664 miles per hour.
You can expect minutes and seconds to both be integers, but miles will be a oat. The two outputs
for the Pace must both be integers, so please use integer division and remainder operations. Note
that if you have a oat value then the function int gives you the integer value. For example
>>> x = 29.52
>>> y = int(x)
>>> print(y)
29
The output for the Speed will be a oat. (Very soon we will learn methods for shortening the speed
output, but we will not do so for this assignment.) Notice that our solution generates the blank
line before the output of the calculations. When you have tested your code and are sure that it
works, please submit it as Part 2 of Homework 1.
Part 3: Madlibs
In this part you will write a Python program to construct the Madlib given below:
Hello <proper name>,
Good morning! Are you looking forward to a/an <adjective> <noun>?
You will <verb> a lot of <noun> and feel <emotion> when you do.
If you do not, you will <verb> this <noun>.
Did you watch the <noun> this <season>?
Were you <emotion> when the <team-name> won?
Have a/an <adjective> day!
You will ask the user of the program for the missing words | those enclosed in < > | using the
input function. You will then take all the user speci ed inputs, and construct the above Madlib.
(Be sure to reread the Input format for homeworks in this class discussion in the instructions above.)
Make sure your output looks like the above paragraph, except that the missing information is lled
in with the user input. Here is an example run of the program (how it will look at the homework
submission server):
Let’s play MadLibs for Homework 1
Type one word responses to the following:
proper_name ==> Alex
adjective ==> interesting
noun ==> semester
verb ==> write
noun ==> code
emotion ==> proud
verb ==> struggle
noun ==> semester
noun ==> Olympics
season ==> summer
emotion ==> excited
team-name ==> USA
adjective ==> nice
Here is your Mad Lib…
Hello Alex,
Good morning! Are you looking forward to a/an interesting semester?
You will write a lot of code and feel proud when you do.
If you do not, you will struggle this semester.
Did you watch the Olympics this summer?
Were you excited when the USA won?
Have a/an nice day!
We’ve provided reasonable inputs, but the idea of MadLibs is to input random words and see how
silly the result looks. Try it!
Of course, the program you write will only work for the speci c MadLib we’ve written above. A
more challenging problem, which you will be capable of solving by the end of the semester, is to
write a program that reads in any MadLib, gures out what to ask the user, asks the user, reads
the input, and generates the nal MadLib.
When you have tested your code and you are sure that it works, please submit it as the solution
to Part 3 of the homework.