001package algs24;
002
003import stdlib.StdIn;
004import stdlib.StdOut;
005
006/**
007 * The {@code PMytrHeap} class is the priorityQ class from Question 2.4.24. It
008 * represents a priority queue of generic keys.
009 * 
010 * It supports the usual <em>insert</em> and <em>delete-the-maximum</em>
011 * operations, along with methods for peeking at the maximum key, testing if the
012 * priority queue is empty, and iterating through the keys. For additional
013 * documentation, see <a href="http://algs4.cs.princeton.edu/24pq">Section
014 * 2.4</a> of <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin
015 * Wayne.
016 */
017
018public class MyPtrHeap<K extends Comparable<? super K>> {
019
020        /** Create an empty priority queue */
021        public MyPtrHeap () {
022                // TODO
023        }
024
025        /** Is the priority queue empty? */
026        public boolean isEmpty () {
027                // TODO
028                return true;
029        }
030
031        /** Return the number of items on the priority queue. */
032        public int size () {
033                // TODO
034                return 0;
035        }
036
037        /**
038         * Return the largest key on the priority queue. Throw an exception if the
039         * priority queue is empty.
040         */
041        public K max () {
042                // TODO
043                return null;
044        }
045
046        /** Add a new key to the priority queue. */
047        public void insert (K x) {
048                // TODO
049                return;
050        }
051
052        /**
053         * Delete and return the largest key on the priority queue. Throw an
054         * exception if the priority queue is empty.
055         */
056        public K delMax () {
057                // TODO
058                return null;
059        }
060
061        private void showHeap () {
062                // a method to print out the heap
063                // useful for debugging
064        }
065
066        public static void main (String[] args) {
067                MyPtrHeap<String> pq = new MyPtrHeap<> ();
068                StdIn.fromString ("10 20 30 40 50 - - - 05 25 35 - - - 70 80 05 - - - - ");
069                while (!StdIn.isEmpty ()) {
070                        StdOut.print ("pq:  ");
071                        pq.showHeap ();
072                        String item = StdIn.readString ();
073                        if (item.equals ("-")) StdOut.println ("max: " + pq.delMax ());
074                        else pq.insert (item);
075                }
076                StdOut.println ("(" + pq.size () + " left on pq)");
077
078        }
079
080}