Esc101 Mid Semester Exam - II

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Jacob Oswald Nichols
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1 Esc101 Mid Semester Exam - II Time Allowed: 1 Hour Max Marks: 75 Instructions: 1. Do not turn this page until the bell rings. 2. YOU MUST WRITE YOUR NAME, ROLL NUMBER & SECTION ON EACH SHEET. 3. Please check that there are 7 sheets in this booklet. 4. In all there are 5 problems in this question booklet, each having two parts. 5. You have to answer on this booklet itself in the specified space. 6. You may use the reverse-side (left) of the sheet for rough work. All your writings on reverse side of the sheet shall be ignored. 7. At the end of the exam, your answer-book will be collected at your seat itself by the invigilator. Warning: Any act of cheating/copying shall be severely dealt with, so refrain from it. Page 1 of 8

2 Question #1.a) What will happen when you attempt to compile and run the following code? Choose the right alternative giving reason. [4] Marking: Full marks if correct reason otherwise 0. public class Q1a{ Q5a h = new Q5a(); private Q5a(){ for(int i=0; i<10; i++){ System.out.print(i + ); Options: 1) Compilation error: Constructors cannot be declared private 2) Run time error: Constructors cannot be declared private 3) Compiles and runs giving output: ) Compiles and runs giving output: Answer: Option 4. Reason: Here the main function is in the same class as the constructor; so it can access the private methods. Question #1.b) This program prints the max, sum and average of two arrays. Fill in the blanks. (NOTE: You are not expected to write the output.) [11] Marking: 1 mark for each correct fill up. class Q1b{ public static double [] method (double [] arr){ double [] result = new double [3]; result[0] = 0.0; result[1] = arr[0]; for(int i=0; i<arr.length; i++){ result[0] += arr[i]; result[1] = result[1] > arr[i]? result[1] : arr[i]; result[2] = result[0] / arr.length; return result; public static double [] method1 (double [] arr1, double [] arr2){ double [] result1 = method(arr1); double [] result2 = method(arr2); double [] result = new double [3]; result[0] = result1[0] + result2[0]; result[1] = result1[1] > result2[1]? result1[1] : result2[1]; result[2] = ((result1[2] * arr1.length)+(result2[2] * arr2.length)) /(arr1.length + arr2.length); return result; public static void Calculate(double [] arr1, double [] arr2){ double [] result = method1(arr1, arr2); System.out.println("Sum of elements of two arrays: " + result[0]); System.out.println("Max of the two arrays: " + result[1]); System.out.println("Average of two arrays: " + result[2]); public static void main(string [] args){ double [] arr1 = {10.0, 12.4, 23.4, 4.5; double [] arr2 = {4.0, 8.4, 2.5, 3.4, 14.5, 2.8; Calculate(arr1, arr2); Page 2 of 8

3 Question #2.a) What is the output of the following program? [12] Marking: 2 marks for each correct output class A{ int x; A(){ x = 10; A(int x){ this.x = x; void Print(){ System.out.println(this.x); class B{ double y; A a; B(){ y = 10.0; a = new A(); B(double y){ this.y = y; a = new A(); B(double y, int x){ this.y = y; a = new A(x); B(double y, A a){ this.y = y; this.a = a; void Print(){ System.out.println(this.y); a.print(); class Q2a{ public static void main(string [] args){ B b1 = new B(5.0); B b2 = new B(6.0, 3); A a1 = new A(12); B b3 = new B(3, a1); b1.print(); b2.print(); b3.print(); Answer: Page 3 of 8

4 Question #2.b) What is the output of the following program? [3] Marking: Full marks for pointing some error in that line, otherwise 0. class Q2b{ public static void Print(int [] arr){ for(int i=0; i<arr.length; i++){ System.out.print(arr[i]); public static void main(string [] args){ int [] a = {1,3,5,7; int [] b; b = {2,3,4,5; Print(a); System.out.println(); Print(b); Answer: Error in line "b={2,3,4,5": Illegal Start of Expression. Question #3.a) We wish to write a program to swap two elements of an array. Use of a temporary variable is not allowed. Complete the program given below. [Assumption: addition and subtraction of the given two numbers do not lead to overflow or underflow] [7] Marking: 1 mark for each correct fill up. class Q3a{ public static void swap(int a[], int x, int y){ a[x] = a[x] + a[y]; a[y] = a[x] - a[y]; a[x] = a[x] - a[y]; int p[] = {1, 2, 3, 4, 5, 6, 7, 8; //invoke the method to swap 3rd and 7th elements of array p swap(p, 2, 6); Page 4 of 8

5 Question #3.b) One can have a partially filled array. A variable datasize, can be used to keep track of number of elements that have been filled. When we remove an element from a partially filled array, all the subsequent elements must be moved ahead and the datasize must be reduced. Complete the code below to achieve this effect. [8] Marking: There are two possible solutions. Any of them is accepted. Marking is as follows: 2 marks for the first blank 1 for each of the next four blanks 2 marks for the last blank. PLEASE NOTE: There was an error in the previous solutions. Instead of p[i] = p[i+1], we ll have p[i-1] = p[i] since p[datasize] might overflow. Also, the other indices are updated accordingly. There can be some other variants of the solution. If k is assumed as 1, 2,... class Q3b{ int p[] = new int [20]; int datasize = 10; //number of elements for (int i=0; i<datasize; i++) p[i]=i; int k = 7; // remove kth element and move all subsequent elements ahead // FILL IN THE CODE BELOW if (k<=datasize){ marks for (int i=k; i<datasize; i++) marks p[i-1] = p[i]; marks else Another Solution: datasize = datasize - 1; If k is assumed as 0, 1, 2,... System.out.println("Element not filled"); marks class Q3b{ int p[] = new int [20]; int datasize = 10; //number of elements for (int i=0; i<datasize; i++) p[i]=i; int k = 7; // remove kth element and move all subsequent elements ahead // FILL IN THE CODE BELOW if (k<=datasize-1){ marks for (int i=k+1; i<datasize; i++) marks p[i-1] = p[i]; marks else datasize = datasize - 1; System.out.println("Element not filled"); marks Page 5 of 8

6 Question #4.a) Given below is the queue class as discussed in the lecture. Fill in the blanks. [6] Marking: 1 mark for each correct fill up. class Queue{ char q[]; // this array holds the queue int putloc, getloc; // the put and get indices Queue(int size) { q = new char[size+1]; // allocate memory for queue putloc = 0; getloc = 0; boolean isempty(){ if (getloc == putloc) return true; else return false; boolean isfull(){ if (putloc == q.length-1) return true; else return false; void put(char ch){ if (isfull()) { System.out.println(" --Queue is full."); return; putloc++; q[putloc] = ch; char get(){ if (isempty()){ System.out.println(" --Queue is empty."); return (char) 0; getloc++; return q[getloc]; Page 6 of 8

7 Question #4.b) The following program has a method BubbleSort1 which implements bubble sort. It has been observed that it performs more iterations than required. So, another modified version of it is given which exits as soon as it finds that the array is sorted. Complete the method BubbleSort2. Also write the output of the program. Marking: 1 mark for each correct fill up 2+2 marks for the outputs class BSort{ public static void swap(int [] arr, int i, int j){ int temp = arr[i]; arr[i] = arr[j]; arr[j] = temp; public static void BubbleSort1(int [] arr){ int size = arr.length; int counter = 0; for(int a=1; a < size; a++){ for(int b=size-1; b>=a; b--){ if(arr[b-1] < arr[b]){ swap(arr, b, b-1); counter++; System.out.println("Counter1: " + counter); public static void BubbleSort2(int [] arr){ int size = arr.length; boolean flag; int counter = 0; for(int a=1; a < size; a++){ flag = false; for(int b = size-1; b>=a; b--){ if(arr[b-1] < arr[b]){ swap(arr, b, b-1); flag = true; counter++; if(!flag) break; System.out.println("Counter2: " + counter); int nums1[] = { 99, -10, 18, -978, -345, 453, 23, 78; int nums2[] = { 99, -10, 18, -978, -345, 453, 23, 78; BubbleSort1(nums1); BubbleSort2(nums2); Answer: Counter1: 28 Counter2: 25 [9] Page 7 of 8

8 Question #5.a) Write the output of the following program. [5] Marking: 1 mark for each correct fill up. public class Q5a { double method(int i) { return i; boolean method(boolean b) { return!b; static double method(int x, double y) { return x + y + 1; static double method(double x, double y) { return x + y + 3; public static void main(string [] args) { System.out.println(method(10, 20)); System.out.println(method(10, 20.0)); System.out.println(method(10.0, 20)); System.out.println(method(10.0, 20.0)); System.out.println(method(false)); Answer: true Question #5.b) What does the following program do? Also write the output. [10] Marking: 4 marks for the Answer and for the outputs. class Q5b{ public static int Method1(int a, int b){ if(a>b) return a; return b; public static int Method1(int [] arr){ int num = arr[0]; for(int i=1; i<arr.length; i++){ num = Method1(num, arr[i]); System.out.println(num); return num; public static int Method1(int [] arra, int [] arrb){ return Method1(Method1(arrA), Method1(arrB)); public static void main(string [] args){ int [] A = {3, 5, 2, 7, 5, 23, 12, 45; int [] B = {5, 3, 8, 10, 47, 12, 19, 30; System.out.println(Method1(A,B)); Answer: It finds the maximum amongst all the elements of both A and B. Output: Page 8 of 8

Types in Java. 8 Primitive Types. What if we want to store lots of items e.g. midsem marks?

Types in Java. 8 Primitive Types. What if we want to store lots of items e.g. midsem marks? Types in Java 8 Primitive Types byte, short, int, long float, double boolean Char Object types: predefined e.g. String ; User-defined via class and constructors What if we want to store lots of items e.g.