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CIS 110 — Introduction to Computer Programming
Fall 2019 — Exam 1 ANSWER KEY
Name: ________________________________________________
Recitation #: ________________________________________________
Pennkey (e.g., eeaton): ________________________________________________
My signature below certifies that I have complied with the University of Pennsylvania’s Code of Academic Integrity in completing this examination.
__________________________________________ __________________________
Signature Date
Instructions:
● Do not open this exam until told by the proctor.
● You will have exactly 110 minutes to take this exam.
● Make sure your phone is turned OFF (not on vibrate!) before the exam starts.
● Food, gum, and drink are strictly forbidden.
● You may not use your phone or open your bag for any reason, including to
retrieve or put away pens or pencils, until you have left the exam room.
● This exam is closed-book, closed-notes, and closed computational devices.
● If you get stuck on a problem, it may be to your benefit to move on to another
question and come back later.
● All code must be written in proper java format, including all curly braces and
semicolons.
● Do not separate the exam pages, with one exception : you must tear off the last
two pages, as they are scratch paper. You must turn in both your exam and
the separated scratch paper. Do not take any sheets of paper with you.
● Only answers on the FRONT of pages will be graded. There are two blank pages
at the end of the exam if you need extra space for any graded answers. You
may use the back of pages for additional scratch work.
● Use a pencil, or blue or black pen to complete the exam.
● If you have any questions, raise your hand and a proctor will come to you.
● When you turn in your exam, you may be required to show ID. If you forgot to
bring your ID, talk to an exam proctor immediately.
● We wish you the best of luck.
1.) The Easy One (2 pts)
Write your name on every exam page. This is in case the pages get separated during grading.
2.) General (7 pts)
For each statement below, note whether it is true or false in the space provided. The first one has been done for you as an example. Write “True” or “False”. No credit will be given for “T” or “F” only. 2.0) main() is always the first method executed when a program is run True 2.1) An if statement must have an else if or an else block False 2.2) a[a.length] will return the last element in the array a False 2.3) (int) 13.4 + 6.6 == 20 False 2.4) (“koala”.charAt(0) - “camel”.charAt(2)) == - (^2) True 2.5) Variable names cannot start with numbers True 2.6) You can have both of the following methods in one class: public static void launch(double power) { ... } public static double launch(double accuracy){ ... } False 2.7) int[] arr = int[18]; is a valid statement False
4.) Welcome to O.W.L.s (15 pts)
Hogwarts has (finally) found a way to use technology inside its premises. You, a newly recruited wizard from the muggle world, have been asked to use your coding skills to help the headmaster set up a system to assign grades to the students for their O.W.L (Ordinary Wizarding Level) exams. The grade schema is as follows: Passing grades: ● O: Outstanding (85 - 100] ● E: Exceeds Expectations (70 - 85] ● A: Acceptable (60 - 70] Failing grades: ● P: Poor (50 - 60] ● D: Dreadful (33 - 50] ● T: Troll [0 - 33] “()“ means exclusive and “[ ]” means inclusive (so, (70 - 85] means if someone gets a score of 85, they get an E, but if someone gets a 70, they get an A (because 70 is not included in E). Write a function, gradeOWLs(), taking in a double array of numeric scores and returning a char array of their corresponding letter grades (in the same order). public static char[] gradeOWLs(double[] marks) { char[] grades = new char[marks.length]; for (int i = 0; i < marks.length; i++) { if (marks[i] > 85) { grades[i] = ‘O’; } else if (marks[i] > 70) { grades[i] = ‘E’; } else if (marks[i] > 60) { grades[i] = ‘A’; } else if (marks[i] > 50) { grades[i] = ‘P’; } else if (marks[i] > 33) { grades[i] = ‘D’; } else { grades[i] = ‘T’; } } return grades; }
5.) Game Night (15 pts)
Professor Eaton and Professor Mally are playing a game. The rules are as follows: ● The game has 9 rounds, and in each round, a random integer between 1 (inclusive) and 200 (exclusive) is generated. ○ If this integer is even, Professor Eaton gets a point. ○ If this integer is odd, Professor Mally gets a point. ○ If this integer is evenly divisible by nine, no one gets a point. ○ If the integer 110 appears, the game ends immediately. Whoever has the most points at the end of the game wins; ties will go to Professor Eaton (alphabetically). The function below simulates this game and returns a String containing the name of the winning professor. Please fill in the blanks to complete the function. public static String professorGame() { int eatonPoints = 0; int mallyPoints = 0; for (int i = 0 ; i < 9 ; i++) { int rand = (int) (Math.random() * 199 ) + 1 ; if (rand == 110) { break; } else if (rand % 9 == 0) { continue; } else if (rand % 2 == 0) { eatonPoints++; } else { mallyPoints++; } } if (eatonPoints >= mallyPoints) { return "Eaton"; } else { return "Mally"; } }
String[] holidayDrinks = {"pumpkinSpookLatte", "candyCaneCappuccino"}; int numSongs = 5, currentSong = 2; boolean isHolidaySeason = false; In inStream = new In(filename); while (!inStream.isEmpty()) { String size = inStream.readString(); String drinkName = inStream.readString(); int numFlavors = inStream.readInt(); currentSong = (currentSong * 2) % numSongs; System.out.println("On song " + currentSong + " of " + numSongs); boolean isHolidayDrink = isHolidayDrink(drinkName, holidayDrinks); if (isHolidayDrink) { if (isHolidaySeason) { System.out.println("Happy holidays!"); System.out.println("Here's your " + size + " " + drinkName
- " with " + totalPumps(numFlavors, size)
- " pumps of syrup!"); } else { System.out.println("We're out; have a free coffee."); } } else { System.out.println("Here's your " + size + " " + drinkName
- " with " + totalPumps(numFlavors, size)
- " pumps of syrup!"); } isHolidaySeason = !isHolidaySeason; if (currentSong % 4 == 0) { System.out.println("Your drink is free!"); numSongs++; } else { System.out.println("That'll be $" + (numFlavors+currentSong)); } System.out.println(); } } }
Output of java NightOnTheTowne orders.txt On song 4 out of 5 Checking coldBrew Here's your medium coldBrew with 4 pumps of syrup! Your drink is free! On song 2 out of 6 Checking pumpkinSpookLatte Happy holidays! Here's your small pumpkinSpookLatte with 4 pumps of syrup! That'll be $ On song 4 out of 6 Checking snowCone We're out; have a free coffee. Your drink is free! On song 1 out of 7 Checking candyCaneCappuccino Happy holidays! Here's your secret candyCaneCappuccino with 110 pumps of syrup! That'll be $
public static void maxwell(double x, double y, int n) { if (n > 1) { if (Math.random() < 0.5) { PennDraw.circle(x, y, 1.0 / n); } else { PennDraw.square(x, y, 1.0 / n); } maxwell(x + (1 - x) * .1, y + (1 - y) * .1, n - 1); } } public static void sierra(double x, double y, int n) { if (n > 1) { if (Math.random() < 0.5) { PennDraw.circle(x, y, 0.2); } else { PennDraw.square(x, y, 0.2); } sierra(x + (1 - x) * .1, y + (1 - y) * .1, n - 1); } } public static void michael(double x, double y, int n) { if (n > 1) { PennDraw.circle(x, y, 1.0 / (2 * n)); PennDraw.square(x, 1 - y, 1.0 / ( 3 * n)); michael(x * 2, y + 0.1, n - 1); } } public static void rachel(double x, double y, int n) { if (n > 1) { double r = n * 0.015; if (n % 2 == 1) { PennDraw.circle(x, y, r); } else { PennDraw.square(x, y, r); } rachel(x + r * 2, y, n - 1); rachel(x, y + r * 2, n - 1); } }
8.) Hellewoan Prenkstars (25 pts)
The TAs want to play a Halloween prank on the professors. Their plan is to reverse the order of vowels in every word on the lecture slides (e.g. compiler → cempilor, method → mothed). However, this would be tedious to do by hand, so they’re asking you to write functions to help them. For this question, we will assume all inputs are lowercase and define vowels as only ‘a’, ‘e’, ‘i’, ‘o’, and ‘u’. We will break this problem down into smaller tasks and write a function for each one:
- A function to check if a character is a vowel
- A function to count the vowels in a String
- A function to return an array of the vowels in reverse order
- A function to assemble the altered String The first function we will write determines whether or not a given character is a vowel. Please complete the following function: (For full credit, your function should be only one line of code.) public static boolean isVowel(char c) { return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u'; } Now, using your isVowel() function, write a function to count the number of vowels in a String. (We must do this before we create an array to store the vowels, so we know how large to make the array.) public static int numVowels(String s) { int count = 0; for (int i = 0; i < s.length(); i++) { if (isVowel(s.charAt(i))) { count++; } } return count; } Next, write a function that takes in a String and returns a char array containing the String’s vowels in reverse order. You can do this by iterating over the String from the end until the beginning, and filling the array from the beginning until the end.
