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Key to CSE142 Final, Autumn 2016 handout #23
1. Reference Mystery. The program produces the following output.
2 [12, 8, 5]
5 [2, 2, 5]
16 3
2. Original List Final List
--------------------------------------------------------------
{2, 5, 6, 9} {2, 3, 5, 9}
{1, 3, 3, 5, 8} {1, 2, 4, 7, 8}
{4, 4, 5, 8, 2} {4, 4, 6, 9, 2}
{3, 6, 9, 12, 15} {3, 4, 6, 9, 15}
{2, 4, 6, 8, 10, 12} {2, 3, 5, 8, 12, 12}
3. Inheritance. The output produced is as follows.
d a d d
b 1 b 1 d 1 c 1
b 2 b 2 d 2 d 2
4. Token-Based File Processing. One possible solution appears below.
public static void tallyScores(Scanner input) {
while (input.hasNext()) {
String name = input.next();
System.out.print(name + ":");
int points = 0;
int count = 0;
while (input.hasNextInt()) {
int nextPoints = input.nextInt();
points += nextPoints;
count++;
System.out.print(" " + nextPoints);
}
System.out.println();
double average = (double) points / count;
System.out.println("average = " + average);
}
}
5. Line-Based File Processing. One possible solution appears below.
public static void underline(Scanner input) {
while (input.hasNextLine()) {
String text = input.nextLine();
if (!text.startsWith(".")) {
System.out.println(text);
} else {
System.out.println(text.substring(1));
for (int i = 1; i <= text.length() - 1; i++) {
System.out.print("-");
}
System.out.println();
}
}
}
6. Arrays. One possible solution appears below.
public static int numUnique(int[] list) {
if (list.length == 0) {
return 0;
} else {
int count = 1;
for (int i = 1; i < list.length; i++) {
if (list[i] != list[i - 1]) {
count++;
}
}
return count;
}
}
7. ArrayLists. One possible solution appears below.
public static void rearrange(ArrayList<Integer> list) {
for (int i = 1; i <= list.size() / 2; i++) {
int n = list.get(i);
list.remove(i);
list.add(n);
}
}
8. Critters. One possible solution appears below.
public class Meeseeks extends Critter {
private int count;
private Random r;
private String display;
public Meeseeks() {
count = 0;
r = new Random();
setDisplay();
}
public Action getMove(CritterInfo info) {
count++;
setDisplay();
if (info.getFront() == Neighbor.EMPTY) {
return Action.HOP;
} else if (info.getFront() == Neighbor.SAME) {
return Action.LEFT;
} else {
return Action.INFECT;
}
}
public Color getColor() {
return Color.BLUE;
}
public String toString() {
return display;
}
private void setDisplay() {
if (count % 4 == 0) {
int choice = r.nextInt(2);
if (choice == 0) {
display = "mister";
} else {
display = "meeseeks";
}
}
}
}
9. Arrays. One possible solution appears below.
public static int[] collapse(int[] list) {
int size = list.length / 2;
if (list.length % 2 == 1) {
size++;
}
int[] result = new int[size];
for (int i = 0; i < list.length / 2; i++) {
result[i] = list[i * 2] + list[i * 2 + 1];
}
if (list.length % 2 == 1) {
result[result.length - 1] = list[list.length - 1];
}
return result;
}
10. Programming. One possible solution appears below.
public static void sumCount(int[] data, int[] sum, int[] count) {
for (int i = 0; i < 4; i++) {
sum[i] = 0;
count[i] = 0;
}
for (int i = 0; i < data.length; i++) {
int index = (i % 7 + 1) / 2;
if (data[i] > 0) {
count[index]++;
sum[index] += data[i];
}
}
}
]]>
Stuart Reges
Last modified: Fri Sep 16 16:16:07 PDT 2011