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Key to CSE142 Final, Autumn 2013 handout #25
1. Expression Value
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43 % 15 / 3 + 15 / 2 11
6.2 * 5 / 10 + 3.5 6.6
6 * 2.5 / 4 + (2.3 + 2.7) / 4 5.0
"18" + 3 * 4 + (8 + 5) "181213"
59 % 10 / (2 + 2) * 2.5 / 2 2.5
2. Original List Final List
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{8, 3} {9, 3}
{2, 5, 4} {3, 5, 4}
{3, 4, 5, 7} {3, 5, 5, 7}
{2, 5, 4, 2} {3, 5, 5, 2}
{4, 5, 7, 9, 3} {5, 5, 7, 9, 3}
3. Inheritance. The output produced is as follows.
b b c b
c 1 c 1 c 1 d 1
a 2 b 2 c 2 b 2
4. Token-Based File Processing. One possible solution appears below.
public static void switchData(Scanner input) {
String label = input.next();
System.out.print(label);
while (input.hasNextInt()) {
int n1 = input.nextInt();
if (input.hasNextInt()) {
int n2 = input.nextInt();
System.out.print(" " + n2);
}
System.out.print(" " + n1);
}
System.out.println();
}
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 boolean isFibLike(int[] list) {
for (int i = 2; i < list.length; i++) {
if (list[i] != list[i - 2] + list[i - 1]) {
return false;
}
}
return true;
}
7. ArrayLists. One possible solution appears below.
public static void expand(ArrayList<Integer> list) {
int i = 0;
while (i < list.size()) {
int times = list.remove(i);
int n = list.remove(i);
for (int j = 0; j < times; j++) {
list.add(i, n);
}
i += times;
}
}
8. Critters. One possible solution appears below.
public class Salmon extends Critter {
private Random r;
private String display;
public Salmon() {
r = new Random();
display = "<*>";
}
public Action getMove(CritterInfo info) {
if (info.getFront() == Neighbor.OTHER) {
return Action.INFECT;
} else if (info.getFront() == Neighbor.EMPTY) {
return Action.HOP;
} else if (r.nextInt(2) == 0) {
display = "<L>";
return Action.LEFT;
} else {
display = "<R>";
return Action.RIGHT;
}
}
public Color getColor() {
return Color.PINK;
}
public String toString() {
return display;
}
}
9. Arrays. One possible solution appears below.
public static int[] insert(int[] list1, int[] list2, int index) {
int[] result = new int[list1.length + list2.length];
for (int i = 0; i < index; i++) {
result[i] = list1[i];
}
for (int i = 0; i < list2.length; i++) {
result[index + i] = list2[i];
}
for (int i = index; i < list1.length; i++) {
result[list2.length + i] = list1[i];
}
return result;
}
10. Programming. One possible solution appears below.
public static String encode(String s, int n) {
String result = "";
for (int j = 0; j < n; j++) {
for (int i = 0; i < s.length() - j; i += n) {
result += s.charAt(i + j);
}
}
return result;
}
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Stuart Reges
Last modified: Fri Sep 16 16:16:07 PDT 2011