weiss.nonstandard
Interface PriorityQueue<AnyType extends java.lang.Comparable<? super AnyType>>

All Known Implementing Classes:

BinaryHeap

public interface PriorityQueue<AnyType extends java.lang.Comparable<? super AnyType>>

PriorityQueue interface. Some priority queues may support a decreaseKey operation, but this is considered an advanced operation. If so, a Position is returned by insert. Note that all "matching" is based on the compareTo method.

Nested Class Summary

static interface

PriorityQueue.Position<AnyType> The Position interface represents a type that can be used for the decreaseKey operation.

Method Summary

void	decreaseKey(PriorityQueue.Position<AnyType> p, AnyType newVal) Change the value of the item stored in the pairing heap.
AnyType	deleteMin() Remove the smallest item from the priority queue.
AnyType	findMin() Find the smallest item in the priority queue.
PriorityQueue.Position<AnyType>	insert(AnyType x) Insert into the priority queue, maintaining heap order.
boolean	isEmpty() Test if the priority queue is logically empty.
void	makeEmpty() Make the priority queue logically empty.
int	size() Returns the size.

Method Detail

insert

PriorityQueue.Position<AnyType> insert(AnyType x)

Insert into the priority queue, maintaining heap order. Duplicates are allowed.

Parameters:

x - the item to insert.

Returns:

may return a Position useful for decreaseKey.

findMin

AnyType findMin()

Find the smallest item in the priority queue.

Returns:

the smallest item.

Throws:

UnderflowException - if empty.

deleteMin

AnyType deleteMin()

Remove the smallest item from the priority queue.

Returns:

the smallest item.

Throws:

UnderflowException - if empty.

isEmpty

boolean isEmpty()

Test if the priority queue is logically empty.

Returns:

true if empty, false otherwise.

makeEmpty

void makeEmpty()

Make the priority queue logically empty.

size

int size()

Returns the size.

Returns:

current size.

decreaseKey

void decreaseKey(PriorityQueue.Position<AnyType> p,
                 AnyType newVal)

Change the value of the item stored in the pairing heap. This is considered an advanced operation and might not be supported by all priority queues. A priority queue will signal its intention to not support decreaseKey by having insert return null consistently.

Parameters:

p - any non-null Position returned by insert.

newVal - the new value, which must be smaller than the currently stored value.

Throws:

java.lang.IllegalArgumentException - if p invalid.

java.lang.UnsupportedOperationException - if appropriate.