Deck 3: Selections

Question 1

To create a set that consists of string elements "red", "green", and "blue", use A. new HashSet(new String[]{"red", "green", "blue"})
B) new Set(Arrays.asList(new String[]{"red", "green", "blue"}))
"}))
D) new HashSet({"red", "green", "blue"})

Answer 1

C

Question 2

Suppose List list = new ArrayList(). Which of the following operations are correct? A. list.add(new Integer(100));
B) list.add(new ArrayList());
C) list.add("Red");
D) list.add(new java.util.Date());

Answer 2

C

Question 3

To create a list to store integers, use B. ArrayList list = new ArrayList();
C) ArrayList

Answer 3

A

Question 4

Show the time complexity of the following program:
for (int k = 0; k < 10; k++) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
System.out.print('*');
}
}
}

Question 5

Write a recursive mathematical definition for computing for a positive integer.

Question 6

(Displaying words) Write a program that reads words separated by spaces from a text file and displays words in ascending order. (If two words are the same, display only one). Pass the text filename from the command line.

Question 7

Suppose your program frequently tests whether a student is in a soccer team, what is the best data structure to store the students in a soccer team? A. ArrayList
C) TreeSet
D) LinkedList
E) Vector

Question 8

Suppose the rule of the party is that the participants who arrive later will leave earlier. Which data structure is appropriate to store the participants? B. Array List
C) Queue
D) Linked List

Question 9

Are there any compile errors in (a) and (b)?

Question 10

Which method do you use to remove an element from a set or list named x? B. x.removes(element)
C) x.delete(element)
D) None of the above
E) x.deletes(element)

Question 11

Which of the following is correct to sort the elements in a list lst? A. new LinkedList(new String[]{"red", "green", "blue"})
B) lst.sort()
C) Arrays.sort(lst)

Question 12

Fill in the code in Comparable______ c = new Date(); A.
B)
C)

Question 13

Design an efficient O(logn) time algorithm for computing . (Describe it using a pseudo code)

Question 14

Suppose that set1 (Set) is a set that contains the strings "red", "yellow", "green", and that set2 (Set) is another set that contains the strings "red", "yellow", "blue". Answer the following questions: (All the questions are independent)
What are set1 and set2 after executing set1.addAll(set2)?
What are set1 and set2 after executing set1.add(set2)?
What are set1 and set2 after executing set1.removeAll(set2)?
What are set1 and set2 after executing set1.remove(set2)?
What are set1 and set2 after executing set1.retainAll(set2)?
What is set1 after executing set1.clear()?

Question 15

Show the output of the following program:

Question 16

To find a maximum object in an array of strings (e.g., String[] names = {"red", "green", "blue"}), use A. Arrays.max(names)
B) Collections.max(Arrays.asList(names))
C) Arrays.sort(names)
D) Collections.max(names)
E) None of the above

Question 17

Which of the data types below could be used to store elements in their natural order based on the compareTo method. A. TreeSet
B) Collection
C) HashSet
D) LinkedHashSet
E) Set

Question 18

How many times is the factorial method in Listing 20.1 invoked for factorial(5)? B. 3
C) 5
D) 4

Question 19

Show the printout of the following code:
Test {
main(String[] args) {
Map map = LinkedHashMap();
map.put("123", "John Smith");
map.put("111", "George Smith");
map.put("123", "Steve Yao");
map.put("222", "Steve Yao");
System.out.println("(1) " + map);
System.out.println("(2) " + new TreeMap(map));
}
}

Question 20

To declare an interface named A with two generic types, use A. public interface A(E, F) { ... }
B) public interface A { ... }
D) public interface A(E) { ... }

Question 21

Suppose your program frequently tests whether a student is in a soccer team and also need to know the student's information such as phone number, address, and age, what is the best data structure to store the students in a soccer team? A. ArrayList
C) TreeMap
D) LinkedList
E) HashSet