CS1101X: Programming Methodology

Discussion onPast-Year’s Papers

Past Year's Papers 2

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Past-years’ papers

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AY2005/6 Sem 1 Q4 (1/3) public static boolean lessThan (Point p, Point q) {

if (p.x == q.x && p.y == q.y) return false;

int x, y; for (int i=0; true; i++) { // outer loop x = 0; y = i;

for (int j=0; j <= i; j++) { // inner loop if (x == p.x && y == p.y) return true; if (x == q.x && y == q.y) return false; x++; y--; } } }

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AY2005/6 Sem 1 Q4 (2/3)

a. If p = (3, 2) and q = (4, 5), what is the output of lessThan(p, q)?

b. If p = (6, 3) and q = (4, 5), what is the output of lessThan(p, q)?

Answers:

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AY2005/6 Sem 1 Q4 (3/3)

c. Rewrite the lessThan method to remove all loops.

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AY2005/6 Sem 1 Q5 (1/4)

int[][] number = new int[6][6];

15 22 8 11 59 44

50 64 29 10 34 20

17 86 27 98 57 21

6 16 88 42 36 45

31 26 12 23 82 54

28 66 58 69 41 1

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AY2005/6 Sem 1 Q5 (2/4) for (int i = 0; i < 6; i++) selectionSort( number[i] ); // At this point, fill in table (a) on the content // in the number array.

int[] tempNumber = new int[6]; for (int j = 0; j < 6; j++) { for (int i = 0; i < 6; i++) tempNumber[i] = number[i][j];

selectionSort( tempNumber );

for (int i = 0; i < 6; i++) number[i][j] = tempNumber[i]; } // At this point, fill in table (b) on the content // in the number array.

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AY2005/6 Sem 1 Q5 (3/4)

Table (a) Table (b)

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AY2005/6 Sem 1 Q5 (4/4) static boolean search (int key, int[][] table, int startX, int startY, int endX, int endY) {

if (startX > endX || startY > endY) return _________ ;

int midX = (startX + endX) / 2; int midY = (startY + endY) / 2;

if (key == table[midX][midY]) return __________ ;

if (key < table[midX][midY] )

return

____________________________________________ ;

else

return

____________________________________________ ; }

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AY2004/5 Sem 1 Q1 (1/3) 1: public class dice { 2: 3: int[] freq; 4: 5: public Dice() { 6: freq = new int[7]; // freq[0] is not used 7: } 8: 9: public void getFreq(int face) {10: return freq[face];11: }12: 13: public void setFreq(int face, int value) {14: freq[face] = value;15: }

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AY2004/5 Sem 1 Q1 (2/3)16: 17: public static void main(String[] args) {18: Dice die = new Dice();19: initFreq();20: printFreq();21: }22: 23: public void initFreq() {24: Random num = new Random();25: int face = 0;26: for (int roll = 1; roll == 6000; roll++) {27: int face = 1 + num.nextInt() * 6;28: setFreq(face, getFreq(face));29: }30: }

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AY2004/5 Sem 1 Q1 (3/3)31: 32: public void printFreq() {33: for (int i = 1; i <= 6; ++i) {34: System.out.println ("Face " + i + 35: " has frequency " + getFreq(face));36: }37: }38: }

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AY2004/5 Sem 1 Q2Output:

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AY2004/5 Sem 1 Q3(a)

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AY2004/5 Sem 1 Q3(b)

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AY2004/5 Sem 1 Q4(d)

Covered in lecture #10 Array, slide 19. Adjust the variable names accordingly. public static int numCoins(int amount) { int[] denominations = {100, 50, 20, 10, 5, 1};  int coins = 0; while (amount > 0) {

} return coins;}

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AY2004/5 Sem 1 Q5(a) (1/2)

// Ballimport java.awt.*;public class Ball { private double radius; private Color color;

public Ball() { this(10.0, Color.BLUE); } public Ball(double r, Color c) { setRadius(r); setColor(c); }

public void setRadius(double r) { radius = r; } public void setColor(Color c) { color = c; } public double getRadius() { return radius; } public Color getColor() { return color; }

public boolean equals(Object v) { // to be filled in }}

Part (a): Complete the equals() method.

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AY2004/5 Sem 1 Q5(a) (2/2)Part (a):Part (a): Complete the equals() method.

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AY2004/5 Sem 1 Q5(b) (1/3)

private Point centre; public Point getCentre() { return centre; } public void setCentre(Point p) { centre = p; }

Extend Ball class to BallOn2D, with radius, colour and centre. Centre is an object of class Point.

Write (i) two constructors; (ii) a main method that creates two BallOn2D objects; and (iii) the toString() method.

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AY2004/5 Sem 1 Q5(b) (2/3)

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AY2004/5 Sem 1 Q5(b) (3/3)

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AY2004/5 Sem 1 Q5(c) (1/2)[Recursion]

A prime number is a positive integer whose only distinct factors are 1 and itself. Write a boolean method isPrime(int n) that returns true if n is prime, or false otherwise. This method should simply call another auxiliary method, which you need to write, that employs recursion. [Only partial credit will be given if you change the formal parameter list of the isPrime(int n) method.]

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AY2004/5 Sem 1 Q5(c) (2/2)isPrime(int n)

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AY2004/5 Sem 2 Q1Output:

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AY2004/5 Sem 2 Q2(b)

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AY2004/5 Sem 2 Q4 (1/3)

A B A B A B A B A B A B A B A

Checkered matrices:

@ # @ # # @ # @ @ # @ # # @ # @

Non-checkered matrices:

A B A B A A B A B A A B A B A

@ # # @ # @ @ # # @ @ # @ # # @

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AY2004/5 Sem 2 Q4 (2/3)

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AY2004/5 Sem 2 Q4 (3/3)

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