What is the output of the following?
5: ArrayDeque<Integer> d = new ArrayDeque<>(); 6: d.offer(18); 7: d.offer(5); 8: d.push(13); 9: System.out.println(d.poll() + " " + d.poll());
A.
The offer() method adds an element to the back of the queue.
After line 7 completes, the queue contains 18 and 5 in that order.
The push() method adds an element to the front of the queue.
The element 13 pushes past everyone on the line.
After line 8 completes, the queue now contains 13, 18, and 5, in that order.
Then we get the first two elements from the front, which are 13 and 18, making Option A correct.