CS1020_Midterm_AY1213S2_qns - CS1020 Midterm AY2012/13...

CS1020 Midterm AY2012/13 Semester 2
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NATIONAL UNIVERSITY OF SINGAPORE
SCHOOL OF COMPUTING
MIDTERM TEST FOR CS1020
AY2012/13 Semester 2
CS1020 – Data Structures and Algorithms I
6 March 2013 Time allowed: 1 hour 30 minutes
INSTRUCTIONS TO CANDIDATES
1. This test paper consists of FIFTEEN (15) questions and comprises NINETEEN (19) printed
pages.
2. This is a CLOSE BOOK test. You are allowed to bring in ONE (1) piece of handwritten A4
double-sided reference sheet (no photocopies).
3. Fill in your Matriculation Number above clearly with a pen . Note that your matriculation
number contains a letter at the back, for example: U084321X or A0091234E.
4. Answer all questions.
5. For MCQs (Q1 to Q12), use the OCR form provided. Shade and write down your
matriculation number on the OCR form. You must use 2B pencil to shade/write on the
OCR form, or the grading machine might not be able to register your shading.
6. For questions Q13 to Q15, fill in your answers in the space provided. You may use pencil
or pen to write your answers.
7. You must submit both the OCR form and this document . It is your responsibility to ensure
that you have submitted both to the invigilator at the end of the test.
EXAMINER’S USE ONLY
Section / Question Possible Marks Check
A. MCQs 1-12 48
B. Q 13 6
B. Q 14 16
B. Q 15 30
Total 100
Matriculation number:
(Write using a pen)

CS1020 Midterm AY2012/13 Semester 2
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SECTION A (12 Multiple Choice Questions: 48 Marks)
Each question has only one correct answer. Shade your answers on the OCR form. 4 marks
are awarded for each correct answer; no penalty for wrong answer.
1. Which of the following are NOT valid Java identifiers?
i. $$$
ii. _500
iii. True
iv. final
v. a/b
A. Only (i) and (v)
B. Only (ii) and (iii)
C. Only (ii) and (iv)
D. Only (iv) and (v)
E. None of options (A), (B), (C), (D) is correct.
2. What is the output of the following code?
class TestMystery {
public static int[] mystery(int[] arr) {
for (int i=0; i<arr.length; i++) {
arr[i] *= 2;
}
return arr;
}
public static void main(String[] args) {
int[] arr = {1};
int[] arr2 = mystery(arr);
System.out.println(arr[0] + " " + arr2[0] + " "
+ (arr == arr2));
}
}

3. Given a Book class which contains the instance method getPages() , and a Book object
called harryPotter1 , which of the following is a valid call?