Quiz 06 sample questions and answers

The quiz will have about three questions, and cover material on queues, implementations of queues, and recursion.

In the following method, (i) identify base case(s), (ii) identify the recursive case(s), and (iii) state whether it will always terminate normally, without throwing an exception. If (i) or (ii) are implicit, then note what they depend upon; or, if (i) or (ii) are missing, then note that fact.

Assume that in the first call to allEven(), currentIndex == 0.

public static boolean allEven(List<Integer> list, int currentIndex) {
    if (currentIndex == list.size()) {
        return true;
    }
    else if (list.get(currentIndex) % 2 == 1) {
        return false;
    }
    else {
        return allEven(list, currentIndex + 1);
    }
}

The first two if statements are base cases.

The final else is the recursive case.

The method will terminate normally.

Suppose you have an empty queue of integers, and on that queue you execute the following operations:

• add 3
• add 1
• add 2
• remove
• add 2
• add 1
• add 3
• remove

Show the final contents of the queue. Clearly indicate the front and rear of the queue.

Front to rear: 2, 2, 1, 3

Suppose we have a singly linked-list-based implementation of a Queue<E>, built of Node<E> elements that link to one another. Further suppose it has head and tail instance variables, pointing to the first and last elements of the list, as well as an int size. In other words, it is the implementation we wrote in lecture.

(Be prepared to write any of its instance methods.)

Check your notes from lecture (or the posted lecture notes) for the nontrivial methods.