Self-assessment 07: Sample questions

The self-assessment will have three questions, and cover material on recursion.

In the first two questions, you will demonstrate your ability to read recursive methods. For example, a question might read:

In the following method, (i) identify the implicit and explicit base case(s), (ii) identify the recursive case(s), and (iii) state whether the method will always terminate normally, that is, 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.

static int factorial(int n) {
    if (n == 0) {
        return 1;
    }
    else {
        return n * factorial(n - 1);
    }
}

Assume n >= 0 when first invoked.

In the third question, you will show you can write simple recursive methods given a textual description of their behavior. For example, a question might state:

Write a recursive definition (not the code) for contains on a linked list of Node<E>, starting at a given node, in the style from lecture.

Then, implement boolean contains(Node<Integer> node, int e) using recursion – no explicit loop constructs (for, while) allowed!

(Note that I expect you to be able use recursion to process either singly linked lists or arrays, but not binary trees. You should also be capable of writing boolean contains(int[] array, int i, int value).)

Check your answers here.