Suppose you are given an implementation of a queue of integers. Consider the following function: void…

Question

Suppose you are given an implementation of a queue of integers.

Queue operation definitions: isEmpty(Q) reports whether Q is empty; delete(Q) removes and returns the front element; insert(Q, i) inserts i at the rear.

Consider the following function:

void f(queue Q)
{
    int i;
    if (!isEmpty(Q))
    {
        i = delete (Q);
        f(Q);
        insert(Q, i);
    }
}

What operation is performed by the function f?

Accepted Answer

Correct answer: B — Concept: In recursion, operations placed after the recursive call execute while the call stack unwinds. Values saved before descending are therefore handled in last-saved, first-restored order. For a queue, deleting from the front before recursion and inserting at the rear after recursion changes pairwise order according to that unwinding order. Application: Trace the calls on a concrete queue [1, 2, 3]. The first call deletes 1 and recursively processes [2, 3]. The next call deletes 2 and recursively processes [3]. The next call deletes 3 and reaches the empty-queue base case. During unwinding, 3 is inserted first, then 2, then 1, producing [3, 2, 1]. Cross-check: Each of the n elements is deleted once and inserted once, so the time cost is O(n). The recursion depth is n, so the auxiliary stack space is O(n). Applying the same transformation a second time restores the original order. Result: The function reverses the order of the elements in queue Q.

Answer

A. Leaves the queue Q unchanged

Answer

B. Reverses the order of the elements in the queue Q

Answer

C. Deletes the element at the front of the queue Q and inserts it at the rear keeping the other elements in the same order

Answer

D. Empties the queue Q

Suppose you are given an implementation of a queue of integers. Consider the…