Design a hit counter (class HitCounter) by using the Queue ADT: Assume you are designing a website; your boss asks you to design a program that can count how many hits received in the past minute. You may assume that each hit comes with a timestamp, hits are received in a chronological order, i.e., the timestamp is monotonically increasing, the earliest timestamp starts at 1, and no hits arrive at the same time. In java.

/*Using the following queue interface*/

/** * Interface for a queue: a collection of elements that are inserted * and removed according to the first-in first-out principle. Although * similar in purpose, this interface differs from java.util.Queue. */

public interface Queue {

/**method: size * returns the number of elements in the queue * @return number of elements in the queue */ int size();

/**method: isEmpty * tests whether the queue is empty * @return true if the queue is empty, false otherwise */ boolean isEmpty();

/**method: first * returns, but does not remove, the first element of the queue * @return the first element of the queue (or null if empty) */ T first(); /**method: enqueue * inserts an element at the rear of the queue * @param e the element to be inserted */ void enqueue(T e);

/**method: dequeue * removes and returns the first element of the queue * @return element removed (or null if empty) */ T dequeue(); }