Example Code Ch 13-5
Consider the following operations on a queue data structure that stores int values:
Queue q = new Queue();
q.enqueue(3);
q.enqueue(5);
q.enqueue(9);
System.out.println(q.dequeue()); // d1
q.enqueue(2);
q.enqueue(4);
System.out.println(q.dequeue()); // d2
System.out.println(q.dequeue()); // d3
q.enqueue(1);
q.enqueue(8);
-Refer to Example Code Ch 13-5: After this code executes, how many elements would remain in q?
A) 0
B) 4
C) 5
D) 6
E) 7

Question

Quizplus · Accepted Answer

After the first three enqueues, the queue contains [3,5,9]. 
dequeue() removes and returns the first element of the queue, so d1 is equal to 3 and the queue now contains [5,9]. 
The next two enqueues add to the end of the queue, resulting in [5,9,2,4]. 
dequeue() is called again, removing and returning 5 which makes the queue [9,2,4]. 
dequeue() is called again, removing and returning 9 which makes the queue [2,4]. 
The next two enqueues add to the end of the queue, resulting in [2,4,1,8]. 
So there are 4 elements remaining in the queue.