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Key to CSE142 Final, Spring 2017 handout #19
1.
4 [9, 20, 30, 41]
1 [9, 20, 30, 41]
2 0
2.
Original List Final List
--------------------------------------------------------------
{0, 2, 3} {0, 2, 5}
{1, 1, 4, 5} {1, 1, 3, 7}
{3, 1, 2, 9, 5} {3, 1, 3, 7, 5}
{5, 1, 1, 1, 8} {5, 1, 3, 7, 8}
{2, 1, 1, 2, 3, 4} {2, 1, 3, 7, 3, 7}
3.
marty
marty 1
stuart 2
stuart
stuart 1
stuart 2
marty
zorah 1
stuart 2
stuart
stuart 1
riley 2
4.
public static void runningStats(Scanner input) {
while (input.hasNext()) {
String name = input.next();
int counter = 0;
int sum = 0;
while (input.hasNextInt()) {
int next = input.nextInt();
sum += next;
counter++;
}
System.out.println(name + " ran " + counter + " laps in " +
sum + " seconds");
System.out.println("average lap time: " + (double) sum / counter);
}
}
5.
public static void familyData(Scanner input) {
int families = 0;
while (input.hasNextLine()) {
families++;
String family = input.nextLine();
int plusIndex = family.indexOf("+");
String parent1 = family.substring(0, plusIndex);
String parent2 = family.substring(plusIndex + 1);
System.out.println(parent1 + " and " + parent2);
String kids = input.nextLine();
Scanner kidScan = new Scanner(kids);
System.out.print("offspring: ");
int count = 0;
while (kidScan.hasNext()) {
System.out.print(kidScan.next() + " ");
count++;
}
System.out.println("(" + count + " total)");
}
System.out.println("total families: " + families);
}
6.
public static boolean containsTriple(int[] list) {
for (int i = 0; i < list.length - 2; i++) {
if (list[i] == list[i + 1] && list[i + 1] == list[i + 2]) {
return true;
}
}
return false;
}
7. Several Solutions:
public static void collapse(ArrayList<Integer> list) {
for (int i = 0; i < list.size() - 1; i++) {
int sum = list.get(i) + list.get(i + 1);
list.set(i, sum);
list.remove(i + 1);
}
}
public static void collapse(ArrayList<Integer> list) {
for (int i = 0; i < list.size() - 1; i++) {
list.add(i, list.remove(i) + list.remove(i));
}
}
public static void collapse(ArrayList<Integer> list) {
for (int i = 0; i < list.size() - 1; i++) {
list.set(i, list.remove(i) + list.get(i));
}
}
8.
public class Vulture extends Critter {
private int count;
private int max;
private boolean infected;
public Vulture() {
Random r = new Random();
max = r.nextInt(6) + 1;
infected = false;
count = 0;
}
public String toString() {
return "V";
}
public Color getColor() {
if (infected) {
return Color.BLUE;
} else {
return Color.BLACK;
}
}
public Action getMove(CritterInfo info) {
if (info.getFront() == Neighbor.OTHER) {
infected = true;
return Action.INFECT;
} else {
infected = false;
if (count < max) {
count++;
return Action.HOP;
} else {
count = 0;
return Action.LEFT;
}
}
}
}
9.
public static int[] insertMirror(int[] list1, int[] list2, int index) {
int[] result = new int[list1.length + list2.length * 2];
for (int i = 0; i < index; i++) {
result[i] = list1[i];
}
for (int i = 0; i < list2.length; i++) {
result[i + index] = list2[list2.length - 1 - i];
result[i + index + list2.length] = list2[i];
}
for (int i = index; i < list1.length; i++) {
result[i + list2.length * 2] = list1[i];
}
return result;
}
10. Several Solutions:
public static void moveToBack(int[] list, int n) {
for (int i = list.length - 2; i >= 0; i--) {
if (list[i] == n) {
for (int j = i; j < list.length - 1; j++) {
list[j] = list[j + 1];
}
list[list.length - 1] = n;
}
}
}
public static void moveToBack(int[] list, int n) {
int numNonN = 0;
for (int i = 0; i < list.length; i++) {
if (list[i] != n) {
list[numNonN] = list[i];
numNonN++;
}
}
for (int i = numNonN; i < list.length; i++) {
list[i] = n;
}
}
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