Faculty of Science COMP-202A - Foundations of Computing (Fall 2014) - All Sections Final Examination

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1 First Name: Last Name: McGill ID: Section: Faculty of Science COMP-202A - Foundations of Computing (Fall 2014) - All Sections Final Examination December 9 th, 2014 Examiners: Melanie Lyman-Abramovitch [Section 1 MWF (9:30-10:30)] 18:00-21:00 Juan Camilo Gamboa Higuera [Section 2 TR (13:00-14:30)] Jonathan Tremblay [Section 3 MWF (12:30-13:30)] Instructions: DO NOT TURN THIS PAGE UNTIL INSTRUCTED This is a closed book examination; only a letter-sized (8.5 by 11 ) crib sheet is permitted. This crib sheet can be single or double-sided; it can be handwritten or typed. Non-electronic translation dictionaries are permitted, but instructors and invigilators reserve the right to inspect them at any time during the examination. Besides the above, only writing implements (pens, pencils, erasers, pencil sharpeners, etc.) are allowed. The possession of any other tools or devices is prohibited. Answer all questions on the scantron sheet. This examination has 30 pages including this cover page, and is printed on both sides of the paper. On page 22, you will find information about useful classes and methods. You may detach the Appendix (page 22 onwards) from the examination if you wish. The Examination Security Monitor Program detects pairs of students with unusually similar answer patterns on mulitple-choice exams. Data generated by this program can be used as admissible evidence, either to initiate or corroborate an investigation or a charge of cheating under Section 16 of the Code of Student Conduct and Disciplinary Procedures. MAKE SURE TO WRITE YOUR NAME AND STUDENT ID ON THE SCANTRON AS WELL AS TO FILL IN THE BUBBLE PROPERLY AT THE BEGINNING OF THE EXAM. MARKS WILL BE DEDUCED IF INFORMATION IS MISSING. Scoring The exam will be scored as follows: 1. Questions 1 to 9 are worth 1 point each 2. Questions 10 to 44 will be worth 2 points each 3. Questions 45 to 65 will be worth 1.5 points each Version-0

2 COMP-202A - Fall Final Examination - Version-0 Page 2 True/False Section (1 point each) 1. Object oriented programming paradigm is useful because it allows us to write more efficient programs (in terms of running time). (A) FALSE (B) TRUE 2. In a class that defines a new data type, you will not get a compile-time error if you do not define a constructor. (A) TRUE (B) FALSE 3. In a class, a non-static (instance) method can access static class variables. (A) TRUE (B) FALSE 4. In Java, each object gets its own copy of the static class variables. (A) FALSE (B) TRUE 5. Inside a class, you can declare multiple methods with the same name, provided that all such methods have different input arguments. (A) TRUE (B) FALSE 6. Inside a class, you can declare multiple methods with the same name, and the same input arguments, provided that all such methods have a different return type. (A) FALSE (B) TRUE

3 COMP-202A - Fall Final Examination - Version-0 Page 3 7. Consider the Node class in the appendix. The following code Node[] mynodes = new Node[10]; for( int i = 0; i < mynodes.length - 1; i++ ) mynodes[i] = new Node(i); mynodes[i].setnext(mynodes[i+1]); will produce an array of 10 Node objects. Each Node will have its next attribute pointing to the next Node in the array (except for the last one, which has next = null). (A) FALSE (B) TRUE 8. What is printed by the following code? String str1 = null; String str2 = "abc"; System.out.println(str2.equals("abc") && str1.equals(null)); (A) TRUE (B) FALSE 9. After executing this code int a = 57; int b = 43; a += b; b = a - b; a -= b; a += b; b = a - b; a -= b; a += b; b = a - b; a -= b; the values of a and b will be swapped. (A) TRUE (B) FALSE

4 COMP-202A - Fall Final Examination - Version-0 Page 4 Regular multiple choice (2 points each) 10. What is printed at the end of this piece of code? int num; for (num = 1; num <= 10; num++) System.out.println(num); (A) 11 (B) 10 (C) "" (D) 9 (E) This gives a compiler error 11. How many times does the letter K get printed in the following code? for (int i = 0; i < 5; i++) System.out.println("K"); for (int j = 0; j < i; j++) System.out.println("K"); System.out.println("K");; (A) 20 (B) 5 (C) 10 (D) 0 (E) 25

5 COMP-202A - Fall Final Examination - Version-0 Page What will the following print? public class Test public static void main (String [] args) boolean b1 = true; boolean b2 = false; boolean b3 = true; if ((b1 && b2) (b2 && b3) b2) System.out.print("ok "); if ((b1 && b2) (b2 && b3) (b1 b2)) System.out.println("dokey"); (A) dokey (B) ok dokey (C) ok (D) No output is produced (E) Compile-time error 13. Given the following boolean expression: (!a && b) ==!(a b) And given the following value combinations for a and b: I. a = true, b = true II. a = true, b = false III. a = false, b = true IV. a = false, b = false For which of the combinations does the above boolean expression evaluate to true? (A) I and II. (B) I and III. (C) II and III. (D) I, II, and IV. (E) II and IV. 14. Which of the following are correct array declarations? I. public static int [5] a; II. public int[] a; III. private final int[] a = 1, 3; (A) II and III. (B) None. (C) All. (D) I and III. (E) I and II.

6 COMP-202A - Fall Final Examination - Version-0 Page Which of the following Java expressions has a value of 0? I. 1.0/2 II. (int) 1.0 / 2.0 III. (int) 1.0 / 2 IV. (int) (1.0 / 2) (A) III and IV. (B) II, III, and IV. (C) II. (D) III. (E) II and IV. 16. The following method takes two integer arrays and a target integer as input. It is supposed to return true if there is an element from the first array and an element from the second array whose sum is the target integer. For instance, given arrays a=[1,4,3] and b=[2,6,3] and target 7, the method should return true because a[1]+b[2] = 4+3 = 7. However, if the target is 8, it should return false, as no element in array a, added with an element of array b results in 8. What should be the body of this method? public static boolean foo (int[] a, int[] b, int target) // What should go here? (A) for(int j = 0; j < b.length; j++) for(int i = 0; i < a.length; i++) if(a[i] + b[j] == target) return true; return false; (B) for(int i = 0; i < a.length + b.length; i++) if(a[i] + b[i] == target) return true; else return false; (C) for(int i = 0; i < a.length; i++) if(a[i] + b[i] == target) return true; else return false; (D) for(int i = 0; i < a.length + b.length; i++) if(a[i] + b[i] == target) return true; return false;

7 COMP-202A - Fall Final Examination - Version-0 Page 7 (E) for(int i = 0; i < a.length; i++) for(int j = 0; j < b.length; j++) if(a[i] + b[j] == target) return true; else return false; 17. What does the following piece of code print? public class Test public static void main(string[] args) int[] a = 2,4,6,8; for(int i = 0; i < a.length; i++) int[] b = foo(a); System.out.print( b[i] + " "); public static int[] foo(int[] array) for(int i = 0; i < array.length; i++) array[i]++; return array; (A) (B) (C) It would give compile-time error. (D) (E) It would give run-time error.

8 COMP-202A - Fall Final Examination - Version-0 Page What kind of exception would be caught below? public class Test public static void main(string[] args) try String[] s = new String[3]; s[1] = "Hello "; s[2] = "World "; for(int i = 0; i <= s.length - 1; i++) System.out.print(s[i].length()); catch(exception e) System.out.println(e); (A) NullPointerException (B) No exception would be caught. (C) ArrayIndexOutOfBoundsException (D) NumberFormatException (E) InputMismatchException 19. Suppose we have the following two classes in separate files. public class Brownie private int weight; private int calories; private boolean isyummy; public void eat() weight = 0; calories = 0; isyummy = Math.random() > 0.5; public class ILoveBrownies public static void main(string[] args) Brownie b1 = new Brownie(); b1.eat();

9 COMP-202A - Fall Final Examination - Version-0 Page 9 Which of the following statements is true? (A) It will compile and run without errors. (B) Brownie class won t compile because the eat method is trying to access a private variable. (C) Brownie class won t compile because there is no constructor. (D) We ll get a run-time error because the variables weight, calories and isyummy are not initialized. (E) Brownie class won t compile because isyummy is declared to have type boolean but in the eat method, we are trying to assign it a non-boolean value. 20. What is the difference between a doubly-linked list and a singly-linked list? (A) Nodes in the doubly-linked list have a reference to the previous node in the list, as well as the next node. (B) The doubly-linked list has a reference to the last node in the list, as well as the first node, while the singly-linked list has only one such reference. (C) It is easier to print a singly-linked list. (D) A doubly-linked list can hold twice as much data as a singly-linked list. (E) A doubly-linked list is a chain of lists, while a singly-linked list is a chain of nodes. 21. Recall, a hash function, h, is a function that maps input of any size to output in some finite set. For example, in class we saw a hash function that takes as input any String and outputs a number between 0 and 25, according to the lexicographical ordering of the first letter of the String. What is a collision in the context of hashing? (A) When more than one key is hashed to the same output value. (B) When several keys are the same and entries get over-written. (C) When a key is hashed to a value that is too large to fit in the array. (D) When a key is hashed and the output is the same as the input. (E) When two different hash tables have the same name. Sort 22. Consider the array a = 5,7,1,4,1. If we sort this array using the Selection Sort (code 2) algorithm described in the appendix, what will be displayed the first time the print statement on line 7 executes? (A) [1, 7, 5, 4, 1] (B) [1, 7, 1, 4, 5] (C) Nothing (D) [1, 1, 5, 4, 7] (E) [1, 1, 7, 4, 5] 23. Consider again the array a = 5,7,1,4,1 and the Selection Sort (code 2) algorithm. What is the last value of the variable minpos, before the algorithm exits? (A) 4 (B) 0 (C) 1 (D) 5 (E) 2

10 COMP-202A - Fall Final Examination - Version-0 Page Consider the Insertion Sort (code 3) algorithm described in the appendix. How can we change this code to have the algorithm sort from largest to smallest instead? (A) Change line 7 to: while(j > 0 & & a[j 1] < x) (B) Change line 3 to: for(int i=a.length-1; i > 0; i- -) (C) Change line 12 to: a[i] = x; (D) Impossible (E) Change line 9 to: a[j-1] = a[j]; 25. Consider the Cocktail Sort (code 4) algorithm described in the appendix. What would happen if we removed the code on lines 16-19? (A) This would cause the algorithm to take more steps to complete. (B) This is a logical error (the array will not be sorted). (C) This changes nothing - the code is useless. (D) This would cause a run-time error. (E) This would cause a compile-time error. 26. Consider the Cocktail Sort (code 4) algorithm described in the appendix. If we input the array a = 3,4,2,6,1, what will be printed by the print statement on line 15 the first time it is executed? (A) [3, 2, 4, 6, 1] (B) [3, 2, 4, 1, 6] (C) [3, 4, 2, 1, 6] (D) [1, 2, 3, 4, 6] (E) Nothing 27. Consider the Cocktail Sort (code 4) algorithm described in the appendix. If we input the same array (a = 3,4,2,6,1), what will be printed by the print statement on line 28 the first time it is executed? (A) [3, 2, 4, 1, 6] (B) [1, 3, 2, 4, 6] (C) [2, 3, 4, 1, 6] (D) [1, 2, 3, 4, 6] (E) Nothing 28. Consider the Cocktail Sort (code 4) algorithm described in the appendix. If we input the array (a = 3,4,1,6,2) 1, how many times total will the print statements on line 15 and 28 execute. For example, if line 15 happens four times, and line 28 happens five time, then your answer should be 9. (A) 5 (B) 3 (C) 4 (D) 6 (E) 0 1 This is a different array from the previous question

11 COMP-202A - Fall Final Examination - Version-0 Page Consider the Cocktail Sort (code 4) algorithm described in the appendix. What is the fewest number of lines of code that would have to be added, removed, or changed in order for this algorithm to sort from largest to smallest? (A) 2 (B) 1 (C) 3 (D) Everything inside both for loops. (E) Everything inside the second for loop. Binary answers For the following questions you are to use your choices as they were the representation of a binary number. More precisely, A = 2 4, B = 2 3, C = 2 2, D = 2 1, and E = 2 0 position in a base 2 number. For example if you wanted to answer the number 23, you would translate it first as base 2 number, which is 10111, you would blacken A, C, D and E. 2 Lets look at this process on your answer sheet, we have these 5 circle you can blacken. Normally you only pick one, here you might have to blacken more than one! A B C D E Following the previous example, the answer we want to input is 23, its binary representation is 10111, hence the circle you would blacken are the following: A B C D E Please follow this process for the next 4 questions. 30. What is the following base 10 number, 31, in base 2? 31. What is printed by the following code in base 2? int sum = 0; for(int x = 0; x< 5; x++) sum+=x; System.out.println(sum);

12 COMP-202A - Fall Final Examination - Version-0 Page What is printed by the following code in base 2? public static void main(string[] args) int[] a = 18,-11,4,-8; int[] b = -1,1,-1,-1; Manipulation(a,b); System.out.println(a[0]+a[1]+a[2]+a[3]); public static void Manipulation(int[] b, int[] a) for (int i = 0; i<a.length ; i++) b[i]=a[a.length-i-1] * b[i]; 33. Base 10 is the set of numbers created from the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. Whereas base 2, which is the set of numbers created with 0, 1. We could similarly define base 3 as the ordered set of characters created from X,Y,Z 3. What is the following base 3 number, YXZ, in base 2? Random graph For this section you will need to look at the classes Graph and GraphNode present in the appendix. A Graph consists of a number of nodes, each of which has connections to other nodes in the graph. You can think of nodes as a representation of a person in a social network (e.g. Facebook). The ArrayList connectedto variable in GraphNodes is the list of friends that particular person has. For example, in the following graph, the node 0 is friends with node 1 and 2. On the other hand, node 2 and node 1 are not friends, hence the lack of link In the constructor of the Graph, the process of connecting nodes is randomized. Moreover, we will not allow a node to be connected to itself and we are going to assume that the arguments passed to the Graph constructor respect the following conditions: n > 2, and n > nbconnections. 3 Pay close attention to the character order

13 COMP-202A - Fall Final Examination - Version-0 Page Which line of code would you add to the Graph.java (code 5) on line 18 to pick two random nodes from your array of nodes? These will then be connected to each other. N.B. Math.random() returns a real number (double) between 0 and 1. (A) GraphNode node1 = graph[(int)(math.random() *n)]; GraphNode node2 = graph[(int)(math.random() *n)]; (B) GraphNode node1 = graph[(int)math.random() *n]; GraphNode node2 = graph[(int)math.random() *n]; (C) GraphNode node1 = graph[math.random() *n]; GraphNode node2 = graph[math.random() *n]; (D) int pos = (int)(math.random()*n); GraphNode node1 = graph[pos]; GraphNode node2 = graph[pos]; (E) int pos = (int)math.random()*n; GraphNode node1 = graph[pos]; GraphNode node2 = graph[pos]; 35. Why do we check on line 20 of code 5 that node1 is not equal to node2? N.B. reread the header of this section. (A) We want to make sure that we do not connect a node to itself (B) It serves no real purpose (C) The code is wrong is should be if(node1 == node2) (D) To check if node1 is neighbour with node2 (E) To avoid an infinite loop 36. Please fill the method Explore() in the GraphNode.java (code 6) line 36. This method explores each node that is connected to the evaluated node. This algorithm marks its explored variable to true when entering the node, and will explore every neighbour that was not already explored. This method will then be used to determine the connectivity of the graph. (A) this.explored = true; for (int i = 0; i<connectedto.size() ; i++) if(!connectedto.get(i).explored) connectedto.get(i).explore(); (B) for (int i = 0; i<connectedto.size() ; i++) if(!connectedto.get(i).explored) connectedto.get(i).explore(); (C) this.explored = true; for (int i = 0; i<connectedto.size() ; i++) connectedto.get(i).explore(); (D) for (int i = 0; i<connectedto.size() ; i++) connectedto.get(i).explore(); (E) for (int i = 0; i<connectedto.size() ; i++) if(!connectedto.get(i).explored) connectedto.get(i).explore();

14 COMP-202A - Fall Final Examination - Version-0 Page 14 this.explored = true; 37. Please fill the method CheckConnectivity() in the Graph.java (code 5) on line 41. This method runs an algorithm to check if the graph is connected 4 and prints onto the console true if the graph is connected and false otherwise. Please pay attention to the other methods available. (A) graph[0].explore(); CheckNodes(); System.out.println(this.connected); (B) CheckNodes(); System.out.println(this.connected); (C) for (int i = 0; i<graph.length ; i++) if(graph[i].explored == false) this.connected = false; (D) for (int i = 0; i<graph.length ; i++) if(graph[i].explored == false) this.connected = false; System.out.println(this.connected); (E) graph[0].explore(); CheckNodes(); 38. Imagine we have the following configuration in an instance of graph: If the node 0 is at position 0 in the graph, and we print its content, what would be printed into the console, e.g. System.out.println(graph[0]);? 5. N.B. The ordering of Nodes written after connected to: is unimportant. (A) 0 is connected to: 1, 3, (B) 0 is connected to: 1, 3 (C) 0 is connected to:, (D) 3 is connected to: 0, 1, 2, 3, 4, (E) 1 is connected to: 0, 3 4 A graph which is connected if there is a path from any point to any other point in the graph 5 This implicitly called tostring method

15 COMP-202A - Fall Final Examination - Version-0 Page 15 Cookie and CookieJar class In the next several questions, you will look at the classes Cookie and CookieJar provided in the appendix, and answer some questions about them. In the process, you will add to the classes. You should think of these classes as being written in separate java files in the same folder. 39. Add the proper code to line 8 of the Cookie class (A) public Cookie (String t, int c) (B) public static Cookie (String t, int c) (C) public Cookie (String type, int calories) (D) public void Cookie (String t, int c) (E) public Cookie (this.type, this.calories) 40. Provide the content of the getter method for the calories property (line 15). To make people feel better, the method should return only 90% of the actual calorie value of the cookie. (A) return (int) (0.9 * calories); (B) return 0.9 * calories; (C) return int 0.9 * calories; (D) return calories; (E) return 0.9 * (double) calories; 41. The eat method should go through the cookie jar, find the first cookie of the type given as input and take it out of the jar. It should then return the number of calories of that cookie, or 0 if no cookie of that type is in the jar. What is the correct line of code to be added at line 31? (A) for (int i = 0 ; i < cookies.size() ; i++) (B) if (cookies.gettype(type)) (C) for (int i = 1; i <= cookies.size() ; i++) (D) Nothing is missing (E) while (cookies.size() > 0)

16 COMP-202A - Fall Final Examination - Version-0 Page The bake method of the CookieJar class should take as input arguments the type of cookie to be baked, the number of cookies to be baked, and what the calories of each of these cookies will be (calpercookie). No return value is needed. The bake method should be accessible from other classes. What is the correct method header? (A) public void bake (String type, int number, int calpercookie) (B) private void bake (String type, int number, int calpercookie) (C) public int bake (String type, int number, int calpercookie) (D) public static void bake (String type, int number, int calpercookie) (E) private static void bake (String type, int number, int calpercookie) 43. The bake method should create the number of cookies of the type and calorie as given and then add them to the cookie jar on which the method was called. Which of the below is the correct method body given that the input parameters are named type, number and calpercookie? (A) for (int i = 0 ; i < number ; i++) cookies.add(new Cookie(type, calpercookie)); (B) for (int i = 0 ; i < number ; i++) cookies.add(new Cookie()); (C) cookies.add(number * new Cookie(type, calpercookie); (D) Cookie c = new Cookie(type, calpercookie) cookies.add(number * c); (E) addcookies(type, number, calpercookie); 44. What do lines 50 and 51 print and how many cookies are left in mycj after the last print statement (just before the main method ends)? (A) line 50: 90 line 51: 0 6 cookies left (B) line 50: 270 line 51: 0 4 cookies left (C) line 50: 100 line 51: cookies left (D) line 50: 90 line 51: cookies left (E) line 50: 90 after that the program crashes

17 COMP-202A - Fall Final Examination - Version-0 Page 17 Coding Section (1.5 points each) In this section you are to write methods that use multiple questions, one line of code per question. The combination of questions can then form the whole method. Make sure you explore all of the questions that define one method before deciding on your answer, as the obvious first choice might not be the right one. Also, do not forget the documentation in the Appendix at the back as it may help for some of these questions. Coding Question - Counting the elements in a list that have a given value The appendix shows a simple List class for integers. The class maintains only a reference to the first element (start) of the list but not the last element of the list. The class so far contains the constructor, a method to add an element to the front of the list, and the tostring method. The elements of the list are of type Node. You can find the Node class also in the appendix. You have to write an additional method for this class that takes as input an integer and returns how often this integer appears in the list. For example, if the list contains 2, 4, 20, 4, 2, 4 and 2 is the input, then the result is 2. If the input is 4, then the result is 3, and when the input is 1, the result should be 0. Use the following 8 questions to write your code. Pay close attention to how your answers group together with each other. 45. Line 1 (A) public int countvalue(int value) (B) public static void countvalue() (C) public void countvalue(int value) (D) public int countvalue(node n) 46. Line 2 (E) public static int countvalue(int value) (A) Node current = this.start; (B) first.value = value; (C) this.start = current; (D) Node current = new Node(value); 47. Line 3 (E) Node n = null; (A) int counter = 0; (B) int counter; (C) if (current == null); (D) if (current!= null); 48. Line 4 (E) while (current!= null) (A) while (current!= null) (B) return; (C) counter = current.getvalue(); (D) counter++; (E) counter = 1;

18 COMP-202A - Fall Final Examination - Version-0 Page Line 5 (A) if (current.getvalue() == value) (B) else (C) return counter; (D) while (current!= null) (E) current = current.nextvalue(); 50. Line 6 (A) counter++; (B) counter = counter + current.getvalue(); (C) return counter; (D) start = null; (E) while(current.getnext() == null) 51. Line 7 (A) current = current.getnext(); (B) (C) return current.getvalue(); (D) counter--; (E) start = current.getnext(); 52. Line 8 (A) return counter; (B) return ; (C) (D) current = current.getnext(); (E) break; Coding Question - Display triangle You are to write a method named Triangle that takes as input an integer height and prints a triangle of that height. This method should be callable from another method, for instance, from the main method. For example if the input is 4, the following is printed on the console: * *** ***** ******* Use the 7 following questions to write your code. Pay close attention to how your answers group together with each other.

19 COMP-202A - Fall Final Examination - Version-0 Page Line 1 (A) public static void Triangle(int height) (B) public static int Triangle(int height) (C) public static void Triangle() (D) public static float Triangle() (E) public static free Triangle(boolean free) 54. Line 2 (A) for (int i = 0; i<height ; i++) (B) for (int i = height; i>0 ; i--) (C) for (int i = 0; i<height/2 ; i--) (D) for (int i = 1; i<height ; i--) (E) for (int i = 1; i>=height/2 ; i+=10) 55. Line 3 (A) for (int j = 0; j< height - i-1; j++) (B) for (int j = 0; j< height - i * 2; j++) (C) for (int j = 0; j< height ; j++) (D) for (int j = height; j< height - i; j+=height) (E) for (int j = 0 ; j< 2 * height; j+=height) 56. Line 4 (A) System.out.print(" "); (B) System.out.print(""); (C) System.out.print("*"); (D) System.out.print("\n"); (E) System.out.print("null"); 57. Line 5 (A) for (int j = 0; j< i*2+1; j++) (B) for (int j = -i*2; j<= i*2; j++) (C) for (int j = i; j<= i*2; j+=i) (D) for (int j = 0; j<= i*2; j++) (E) for (int j = -i; j> i; j++) 58. Line 6 (A) System.out.print("*"); (B) System.out.print(" "); (C) System.out.print("\n"); (D) System.out.print(";)"); (E) System.out.print(""); 59. Line 7 (A) System.out.print("\n"); (B) System.out.print("*"); (C) System.out.print("null"); (D) System.out.print(" "); (E) System.out.print("");

20 COMP-202A - Fall Final Examination - Version-0 Page 20 Coding Question - Sum square difference Write a method called sumsqdiff that takes an input an integer upperbound and returns the difference between the square of the sum and the sum of the squares of all natural numbers, up to and including that bound. For example, if the upperbound is 10, your method should compute the following: ( i) i=1 i=1 ( ) 2 ( ) i 2 (1) Use the 6 following questions to write your code. Pay close attention to how your answers group together with each other. 60. Line 1 (A) public static int sumsqdiff(int upperbound) (B) public static void sumsqdiff(int upperbound) (C) public static int sumsqdiff(double upperbound) (D) public static int sumsqdiff() 61. Line 2 (E) public static double sumsqdiff(double upperbound) (A) int sum = 0; int sqsum = 0; (B) int sum = 1; int sqsum = 1; (C) int sum = 0; int sqsum = upperbound; (D) int sum = 0; double sqsum = upperbound; 62. Line 3 (E) int sum = 1; double sqsum = upperbound; (A) for(int i=1; i<=upperbound; i++) (B) for(int i=1; i<=sqsum; i++) (C) for(int i=0; i<=upperbound; i++) (D) for(int i=1; i<upperbound; i++) 63. Line 4 (E) for(int i=sqsum; i>=0; i--) (A) sum+=i; (B) sqsum+=i; (C) sum+=sqsum; (D) sqsum+=2*i; (E) sum++;

21 COMP-202A - Fall Final Examination - Version-0 Page Line 5 (A) sqsum=sqsum + i*i; (B) sqsum+=i; (C) sqsum=sqsum*sum*i; (D) sqsum=sqsum + i*sum; (E) sqsum*=sqsum; 65. Line 6 (A) return sum*sum - sqsum; (B) result = sum*sum - sqsum; (C) result = sum - sqsum; (D) return sum*sum + sqsum; (E) return = sqsum - sum*sum;

22 COMP-202A - Fall Final Examination - Appendix Page 22 SUMMARY OF JAVA STANDARD LIBRARY METHODS FOR SELECTED CLASSES Arrays (package java.util.arrays Methods: public int[] copyofrange(int[] original, int from, int to): Returns a subset of the original starting at from and finishing at to, excluding to. to might lie outside of the array. String (package java.lang) Methods: public boolean equals(object anobject): Compares this String to anobject. public int length(): Calculates the length of this String. public char charat(int i): Gets the char at position i of the String. Note that counting starts from 0 so that to get the first character of the String you should input i equals 0. public boolean equalsignorecase(string anotherstring): Compares, ignoring case considerations, this String to anotherstring. public int compareto(string anotherstring): Compares this String to anotherstring lexicographically; returns a negative value if this String occurs before anotherstring, a positive value if this String occurs after anotherstring, and 0 if both Strings are equal. public int comparetoignorecase(string anotherstring): Compares, ignoring case considerations, this String to anotherstring lexicographically; returns a negative value if this String occurs before anotherstring, a positive value if this String occurs after anotherstring, and 0 if both Strings are equal. public String substring(int start, int finish): Returns a new String composed of the this String starting from index start and up to, but not including index of finish public String replace(char c, char d) : Returns a new String with all occurrences of the character c in the this String replaced by the character d. public char[] tochararray(): Converts this String to a new character array. File (package java.io) Methods: public FileSstring pathname): Creates a new File instance that corresponds to the given pathname. Scanner (package java.util) Methods: public Scanner(Inputstream source): Constructs a new Scanner that produces values scanned from the specified input stream. public Scanner(File f): Constructs a new Scanner that produces values scanned from the specified File public double nextdouble(): Scans the next token of the input as a double. public boolean nextboolean(): Scans the next token of the input as a boolean. public int nextint(): Scans the next token of the input as an int. public String nextline(): Advances this Scanner past the current line and returns the input read. public boolean hasnextline(): Checks whether there are further lines left to scan. PrintStream (package java.io) Methods: public void print(boolean b): Prints boolean value b. public void print(double d): Prints double value d. public void print(int i): Prints int value i. public void print(object o): Prints Object o. public void print(string s): Prints String s. public void println(): Terminates the current line by writing the line separator string. public void println(boolean b): Prints boolean value b and then terminates the line. public void println(double d): Prints double value d and then terminates the line. public void println(int i): Prints int value i and then terminates the line. public void println(object o): Prints Object o and then terminates the line. public void println(string s): Prints String s and then terminates the line. Math (package java.lang) Methods: public static double pow(double a, double b): Returns the value of a raised to the power of b. public static double sqrt(double a): Returns the correctly rounded positive square root of double value a. public static double random(): Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0. public static double exp(double a): Returns Euler s number e raised to the power of double value a. (base e) of double value a. of double value a.

23 COMP-202A - Fall Final Examination - Appendix Page 23 1 public static void bubblesort(int[] array) 2 3 int n = array.length; 4 boolean madeswap = true; 5 while(madeswap) 6 7 madeswap = false; 8 //Scanning 9 for (int j = 0; j < n - 1; j++) if (array[j] > array[j+1] ) //Swapping 14 swap(array,j,j+1); 15 madeswap = true; public static void swap(int[] a, int i, int j) int t = a[i]; 24 a[i] = a[j]; 25 a[j] = t; 26 Code 1: Bubble Sort

24 COMP-202A - Fall Final Examination - Appendix Page 24 1 public static void selectionsort(int[] a) 2 3 for(int start = 0; start<a.length; start++) 4 5 int minpos = smallest(a,start); 6 swap(a,start,minpos); 7 System.out.println(Arrays.toString(a)); public static int smallest(int[] a, int starter) int minpos = starter; 14 for (int i = starter; i<a.length ; i++) if(a[i]<a[minpos]) minpos = i; return minpos; public static void swap(int[] a, int v, int w) int t = a[v]; 27 a[v] = a[w]; 28 a[w] = t; 29 Code 2: Selection Sort 1 public static void insertionsort(int[] a) 2 3 for(int i = 1; i<a.length; i++) 4 5 int j = i; 6 int x = a[i]; 7 while(j>0 && a[j-1] > x) 8 9 a[j] = a[j-1]; 10 j--; a[j] = x; 13 System.out.println(Arrays.toString(a)); Code 3: Insertion Sort

25 COMP-202A - Fall Final Examination - Appendix Page 25 1 public static void cocktailsort(int[] a) 2 3 boolean swapped = true; 4 while(swapped) 5 6 swapped = false; 7 for(int i=0; i<a.length-2; i++) 8 9 if(a[i] > a[i+1]) swap(a, i, i+1); 12 swapped = true; System.out.println(Arrays.toString(a)); 16 if(!swapped) break; for(int j=a.length-2; j>=0; j--) if(a[j] > a[j+1]) swap(a, j, j+1); 25 swapped = true; System.out.println(Arrays.toString(a)); public static void swap(int[] a, int v, int w) int t = a[v]; 36 a[v] = a[w]; 37 a[w] = t; 38 Code 4: Cocktail Sort

26 COMP-202A - Fall Final Examination - Appendix Page 26 1 public class Graph 2 3 GraphNode[] graph; 4 boolean connected; 5 public Graph(int n, int nbconnections ) 6 Graph.connected = false; 7 //set the nodes 8 graph = new GraphNode[n]; 9 10 for (int i = 0; i<graph.length ; i++) //Create the nodes 11 graph[i] = new GraphNode(i); int counterconnections = 0; while(counterconnections<nbconnections) 17 //Get two random nodes 18 //PLEASE FILL THIS if(node1!= node2) 21 boolean connected = node1.connected(node2); 22 if(! connected) 23 node1.connect(node2); 24 node2.connect(node1); 25 counterconnections++; public void CheckNodes() 31 //Assume this is connected 32 this.connected = true; 33 //Check if there is one node that was not explored 34 for (int i = 0; i<graph.length ; i++) 35 if(graph[i].explored == false) 36 this.connected = false; public void CheckConnectivity() 41 //PLEASE FILL THIS public String tostring() 44 String s = "Graph\n"; 45 for (int i = 0; i<graph.length ; i++) 46 s+= graph[i].tostring() + "\n"; return s; Code 5: Random graph class

27 COMP-202A - Fall Final Examination - Appendix Page 27 1 import java.util.*; 2 3 public class GraphNode 4 5 ArrayList<GraphNode> connectedto; 6 boolean explored; 7 int id; 8 9 public GraphNode(int i) connectedto = new ArrayList<GraphNode>(); 12 //list of neighbours 13 explored = false; 14 id = i; public void Connect(GraphNode toadd) connectedto.add(toadd); public boolean Connected(GraphNode toconnect) if(connectedto.contains(toconnect)) return true; else return false; public void Explore() //PLEASE FILL THIS public String tostring() String s = ""; 41 s+= id + " is connected to: "; 42 for (int i = 0; i<connectedto.size() ; i++) s+= connectedto.get(i).id +", "; return s; Code 6: Node for random graph

28 COMP-202A - Fall Final Examination - Appendix Page 28 1 // This class is used to represent a cookie 2 public class Cookie 3 4 public String type; // The type of cookie: brownie, Xmas cookie,... 5 public int calories; 6 7 // Constructor 8 //... this line is still missing 9 10 this.type = t; 11 this.calories = c; public int getcalories() 15 //... this line is still missing // This class is used to represent a cookie jar 19 public class CookieJar ArrayList<Cookie> cookies; // All the cookies in the jar // Constructor 24 public CookieJar() 25 //... this line is still missing /* go through the cookie jar, find the first cookie of the type given as input and take it out; return the number of calories of that cookie, or 0 if no cookie of that type is in the jar. */ 28 public int boolean eat (String type) Cookie c; 31 //... this line is still missing c = cookies.get(i); 34 if (c.type.equals(type)) 35 cookies.remove(i); 36 return c.getcalories(); return 0; // bake a number of cookies of a certain type 42 //... this method is still missing public class Test 46 public static void main (String [] args) 47 CookieJar mycj = new CookieJar(); // mycj is the new cookie jar. 48 mycj.bake("brownies", 4, 250); 49 mycj.bake("lemon", 3, 100); 50 System.out.println(myCJ.eat("Lemon")); 51 System.out.println(myCJ.eat("Chocolate")); Code 7: Cookie and CookieJar classes

29 COMP-202A - Fall Final Examination - Appendix Page 29 1 public class List 2 3 private Node start; 4 5 public List() 6 7 start = null; public void addlist(int value) Node temp = start; start = new Node(value); 15 start.setnext(temp); public String tostring() String s = ""; 21 Node current = start; 22 while(current!= null) s += current.getvalue() ; 25 if(current.getnext()!= null) 26 s+= "->"; 27 current = current.getnext(); return s; Code 8: List class

30 COMP-202A - Fall Final Examination - Appendix Page 30 1 public class Node 2 3 private int value; 4 private Node next; 5 6 public Node(int value) 7 8 this.value = value; 9 this.next = null; public Node getnext() return this.next; public void setnext(node n) this.next = n; public int getvalue() return value; Code 9: List node class