package algs24;

import stdlib.StdIn; import stdlib.StdOut;

/** * The PtrHeap class is the priorityQ class from Question 2.4.24. * It represents a priority queue of generic keys. * * It supports the usual insert and delete-the-maximum * operations, along with methods for peeking at the maximum key, * testing if the priority queue is empty, and iterating through * the keys. * For additional documentation, see Section 2.4 of * Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne. */

public class PtrHeap> { static class Node { K value; Node parent; Node lchild; Node rchild; } private int size; private Node root; boolean isRoot(Node n){ return n == root; } Node find(int n){ return null; } void exch(Node n1, Node n2) { // only swap items of nodes } @SuppressWarnings("unchecked") /** Create an empty priority queue */ public PtrHeap() { } /** Is the priority queue empty? */ public boolean isEmpty() { return true; }

/** Return the number of items on the priority queue. */ public int size() { return size; }

/** * Return the largest key on the priority queue. * Throw an exception if the priority queue is empty. */ public K max() { return null; }

/** Add a new key to the priority queue. */ public void insert(K x) { return; }

/** * Delete and return the largest key on the priority queue. * Throw an exception if the priority queue is empty. */ public K delMax() { return null; }

private void showHeap() { // a method to print out the heap // useful for debugging }

public static void main(String[] args) { PtrHeap pq = new PtrHeap<>(); StdIn.fromString("10 20 30 40 50 - - - 05 25 35 - - - 70 80 05 - - - - "); while (!StdIn.isEmpty()) { StdOut.print ("pq: "); pq.showHeap(); String item = StdIn.readString(); if (item.equals("-")) StdOut.println("max: " + pq.delMax()); else pq.insert(item); } StdOut.println("(" + pq.size() + " left on pq)");

}

}