structure5
Class SkewHeap<E extends Comparable<E>>

java.lang.Object
  structure5.SkewHeap<E>

All Implemented Interfaces:

MergeableHeap<E>, PriorityQueue<E>

public class SkewHeap<E extends Comparable<E>>
extends Object
implements MergeableHeap<E>

An implementation of a priority queue using skew heaps. Skew heaps allow one to construct heaps dynamically without explictly balancing the heaps. Main operation is a merge. Most operations execute in amortized logarithmic time, but individual operations may take linear time to execute in the worst case.

Example usage:

To print out a list of programmers sorted by age we could use the following:

 public static void main(String[] argv){
        //initialize a new fib heap
        SkewHeap programmers = new SkewHeap();

        //add programmers and their ages to heap
        //ages current of 7/22/2002
        //add programmers and their ages to heap
        //ages current of 7/22/2002
        programmers.add(new ComparableAssociation(new Integer(22), "Evan"));
        programmers.add(new ComparableAssociation(new Integer(19), "Chris"));
        programmers.add(new ComparableAssociation(new Integer(20), "Shimon"));
        programmers.add(new ComparableAssociation(new Integer(21), "Diane"));
        programmers.add(new ComparableAssociation(new Integer(21), "Lida"));    
        programmers.add(new ComparableAssociation(new Integer(20), "Rob"));     
        programmers.add(new ComparableAssociation(new Integer(20), "Sean"));    

        //print out programmers 
        while(!programmers.isEmpty()){
            ComparableAssociation p = (ComparableAssociation)programmers.remove();
            System.out.println(p.getValue() + " is " + p.getKey() + " years old.");
        }
 }
 

Constructor Summary

SkewHeap()
Constructs an empty priority queue.

Method Summary

void	add(E value) Add a value to the priority queue.
void	clear() Remove all the elements from the queue.
E	getFirst() Fetch lowest valued (highest priority) item from queue.
boolean	isEmpty() Determine if the queue is empty.
static void	main(String[] argv)
void	merge(MergeableHeap<E> otherHeap) Merge this heap with another
E	remove() Returns the minimum value from the queue.
int	size() Determine the size of the queue.
String	toString() Construct a string representation of the heap.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

SkewHeap

public SkewHeap()

Constructs an empty priority queue.

Method Detail

getFirst

public E getFirst()

Fetch lowest valued (highest priority) item from queue.

Specified by:

getFirst in interface PriorityQueue<E extends Comparable<E>>

Returns:

The smallest value from queue.

remove

public E remove()

Returns the minimum value from the queue.

Specified by:

remove in interface PriorityQueue<E extends Comparable<E>>

Returns:

The minimum value in the queue.

add

public void add(E value)

Add a value to the priority queue.

Specified by:

add in interface PriorityQueue<E extends Comparable<E>>

Parameters:

value - The value to be added.

size

public int size()

Determine the size of the queue.

Specified by:

size in interface PriorityQueue<E extends Comparable<E>>

Returns:

The number of elements within the queue.

clear

public void clear()

Remove all the elements from the queue.

Specified by:

clear in interface PriorityQueue<E extends Comparable<E>>

isEmpty

public boolean isEmpty()

Determine if the queue is empty.

Specified by:

isEmpty in interface PriorityQueue<E extends Comparable<E>>

Returns:

True if the queue is empty.

merge

public void merge(MergeableHeap<E> otherHeap)

Merge this heap with another

Specified by:

merge in interface MergeableHeap<E extends Comparable<E>>

Parameters:

otherHeap - Heap to be merged with this heap, otherHeap is destroyed by this operation;

toString

public String toString()

Construct a string representation of the heap.

Overrides:

toString in class Object

Returns:

The string representing the heap.

main

public static void main(String[] argv)