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Computer Science 105, S1C 2014 1/4
COMPSCI 105 S1 2014 Tutorial 1: Nested Loops, Arrays
Please download sample code from
http://www.cs.auckland.ac.nz/courses/compsci105ssc/tutorials/
Q1. What is the output of the following code? Run the program and try to understand its output.
private void ex01() {
int[] nums = { 8, 10, 3, 4, 12, 200 };
for (int i = nums.length - 1 ; i >= 1 ; i--) {
if (i == 1) {
} else {
} } }
System.out.println(nums[i]);
nums[i - 1] = nums[i];
System.out.format("%d,", nums[i]);
Q2. Complete the nestedLoops method below such that it generates the following output:
9 8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1 7 6 5 4 3 2 1 6 5 4 3 2 1 5 4 3 2 1 4 3 2 1 3 2 1 2 1 1
Hint: Initially only try to get the numbers printed out correctly and then if you have time attempt to format like above so that there is left padding.
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Computer Science 105, S1C 2014 2/4
private void ex02(){
}
Q3. Given the following code:
int count = 0;
for(int i = 0; i < 10; i += 2) {
for(int j = 0; j < 5; ++j) {
for(int k = 5; k > 0; --k) {
++count;
} } }
System.out.println(count);
What number can we expect to be output?
Q4. A Point object contains two values, namely x and y. Complete the increaseDecreasePointValues() method which decreases the x value by 1 and increases the y value by 2 of each Point object in the 2D Point array which is passed to the method as a parameter. The output of the ex04() method should be:
(1, 2) (1, 3) (1, 4) (2, 5) (2, 3) (2, 3) (3, 6) (6, 8) (3, 2) (4, 2) (7, 6) (4, 1)
(0, 4) (0, 5) (0, 6) (1, 7) (1, 5) (1, 5) (2, 8) (5, 10) (2, 4) (3, 4) (6, 8) (3, 3)
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Computer Science 105, S1C 2014 3/4
private void ex04() {
Point[][] points = create2DPointArray();
print2DPointArray(points);
increaseDecreasePointValues(points);
print2DPointArray(points);
}
private void increaseDecreasePointValues(Point[][] pts) {
}
private Point[][] create2DPointArray() {
Point[][] pointArray = {
{new Point(1, 2), new Point(1, 3), new Point(1, 4)}, {new Point(2, 5), new Point(2, 3), new Point(2, 3)}, {new Point(3, 6), new Point(6, 8), new Point(3, 2)}, {new Point(4, 2), new Point(7, 6), new Point(4, 1)}, };
return pointArray;
}
private void print2DPointArray(Point[][] pts) {
//Code is not shown here, look in the supplied code }
Please send comments and corrections to your tutor
Computer Science 105, S1C 2014 4/4
Q5. Complete the makeAFullCopy() method which returns a full copy of the 2D Point array passed as a parameter.
private void ex05() {
Point[][] points = create2DPointArray();
Point[][] pointsCopy = makeAFullCopy(points);
boolean flag = false;
for (int i = 0; i < points.length; i++) {
for (int j = 0; j < points[i].length; j++) {
if( points[i][j] == pointsCopy[i][j]) {
flag = true;
break;
} } }
System.out.println( (flag) ? "This should not execute."
: "Correctly copied"
);
}
private Point[][] makeAFullCopy(Point[][] pts) { Point[][] ptsCopy;
}
What do you need to watch out for when copying arrays?