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Monday, 23 January 2017

Chapter 23 Exercise 11, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

23.11 (Heap clone and equals ) Implement the clone and equals method in the
Heap class.


import java.util.ArrayList;

public class Exercise11 {

 public static void main(String[] args) throws CloneNotSupportedException {
  Heap<Integer> heap1 = new Heap<>();
  heap1.add(1);
  heap1.add(2);
  heap1.add(3);
  
  Heap<Integer> heap2 = new Heap<>();
  heap2.add(3);
  heap2.add(1);
  heap2.add(2);
  
  
  Heap<Integer> heap3 = new Heap<>();
  heap3.add(2);
  heap3.add(2);
  heap3.add(3);
  
  System.out.println(heap1.equals(heap2));
  System.out.println(heap1.equals(heap3));
  
  @SuppressWarnings("unchecked")
  Heap<Integer> heap4 = (Heap<Integer>) heap1.clone();
  System.out.println(heap1.equals(heap4));
  System.out.println(heap1 == heap4);
 }

 static public class Heap<E extends Comparable<E>> implements Cloneable {
  private java.util.ArrayList<E> list = new java.util.ArrayList<E>();

  /** Create a default heap */
  public Heap() {
  }

  /** Create a heap from an array of objects */
  public Heap(E[] objects) {
   for (int i = 0; i < objects.length; i++)
    add(objects[i]);
  }

  /** Add a new object into the heap */
  public void add(E newObject) {
   list.add(newObject); // Append to the heap
   int currentIndex = list.size() - 1; // The index of the last node

   while (currentIndex > 0) {
    int parentIndex = (currentIndex - 1) / 2;
    // Swap if the current object is greater than its parent
    if (list.get(currentIndex).compareTo(list.get(parentIndex)) > 0) {
     E temp = list.get(currentIndex);
     list.set(currentIndex, list.get(parentIndex));
     list.set(parentIndex, temp);
    } else
     break; // the tree is a heap now

    currentIndex = parentIndex;
   }
  }

  /** Remove the root from the heap */
  public E remove() {
   if (list.size() == 0)
    return null;

   E removedObject = list.get(0);
   list.set(0, list.get(list.size() - 1));
   list.remove(list.size() - 1);

   int currentIndex = 0;
   while (currentIndex < list.size()) {
    int leftChildIndex = 2 * currentIndex + 1;
    int rightChildIndex = 2 * currentIndex + 2;

    // Find the maximum between two children
    if (leftChildIndex >= list.size())
     break; // The tree is a heap
    int maxIndex = leftChildIndex;
    if (rightChildIndex < list.size()) {
     if (list.get(maxIndex).compareTo(list.get(rightChildIndex)) < 0) {
      maxIndex = rightChildIndex;
     }
    }

    // Swap if the current node is less than the maximum
    if (list.get(currentIndex).compareTo(list.get(maxIndex)) < 0) {
     E temp = list.get(maxIndex);
     list.set(maxIndex, list.get(currentIndex));
     list.set(currentIndex, temp);
     currentIndex = maxIndex;
    } else
     break; // The tree is a heap
   }

   return removedObject;
  }

  /** Get the number of nodes in the tree */
  public int getSize() {
   return list.size();
  }
  
  @SuppressWarnings("unchecked")
  @Override
  protected Object clone() throws CloneNotSupportedException {
   Heap<E> newHeap = new Heap<>();
   newHeap.list = (ArrayList<E>) list.clone();
   return newHeap;
  }
  
  
  @SuppressWarnings("unchecked")
  @Override
  public boolean equals(Object obj) {
   if (obj instanceof Heap) {
    return list.equals(((Heap<E>)(obj)).list);
   } else {
    return false;
   }
   
  }
 }

}

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