Package it.unimi.dsi.fastutil.doubles

Class DoubleArrayPriorityQueue

java.lang.Object

it.unimi.dsi.fastutil.doubles.DoubleArrayPriorityQueue

All Implemented Interfaces:

DoublePriorityQueue, PriorityQueue<Double>, Serializable

public class DoubleArrayPriorityQueue
extends Object
implements DoublePriorityQueue, Serializable

A type-specific array-based priority queue.

Instances of this class represent a priority queue using a backing array—all operations are performed directly on the array. The array is enlarged as needed, but it is never shrunk. Use the trim() method to reduce its size, if necessary.

See Also:

• Serialized Form

Implementation Specification:

This implementation is extremely inefficient, but it is difficult to beat when the size of the queue is very small.

Constructor Summary

Constructors

Constructor	Description
DoubleArrayPriorityQueue()	Creates a new empty queue using the natural order.
DoubleArrayPriorityQueue(double[] a)	Wraps a given array in a queue using the natural order.
DoubleArrayPriorityQueue(double[] a, int size)	Wraps a given array in a queue using the natural order.
DoubleArrayPriorityQueue(double[] a, int size, DoubleComparator c)	Wraps a given array in a queue using a given comparator.
DoubleArrayPriorityQueue(double[] a, DoubleComparator c)	Wraps a given array in a queue using a given comparator.
DoubleArrayPriorityQueue(int capacity)	Creates a new empty queue with a given capacity and using the natural order.
DoubleArrayPriorityQueue(int capacity, DoubleComparator c)	Creates a new empty queue with a given capacity and comparator.
DoubleArrayPriorityQueue(DoubleComparator c)	Creates a new empty queue with a given comparator.

Method Summary

Modifier and Type	Method	Description
void	changed()	Notifies the queue that the first element has changed (optional operation).
void	clear()	Removes all elements from this queue.
DoubleComparator	comparator()	Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.
double	dequeueDouble()	Dequeues the first element from the queue.
void	enqueue(double x)	Enqueues a new element.
double	firstDouble()	Returns the first element of the queue.
int	size()	Returns the number of elements in this queue.
void	trim()	Trims the underlying array so that it has exactly size() elements.

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unimi.dsi.fastutil.doubles.DoublePriorityQueue

dequeue, enqueue, first, last, lastDouble

Methods inherited from interface it.unimi.dsi.fastutil.PriorityQueue

isEmpty

Constructor Details

DoubleArrayPriorityQueue

public DoubleArrayPriorityQueue(int capacity,
 DoubleComparator c)

Creates a new empty queue with a given capacity and comparator.

Parameters:

capacity - the initial capacity of this queue.

c - the comparator used in this queue, or null for the natural order.

DoubleArrayPriorityQueue

public DoubleArrayPriorityQueue(int capacity)

Creates a new empty queue with a given capacity and using the natural order.

Parameters:

capacity - the initial capacity of this queue.

DoubleArrayPriorityQueue

public DoubleArrayPriorityQueue(DoubleComparator c)

Creates a new empty queue with a given comparator.

Parameters:

c - the comparator used in this queue, or null for the natural order.

DoubleArrayPriorityQueue

public DoubleArrayPriorityQueue()

Creates a new empty queue using the natural order.

DoubleArrayPriorityQueue

public DoubleArrayPriorityQueue(double[] a,
 int size,
 DoubleComparator c)

Wraps a given array in a queue using a given comparator.

The queue returned by this method will be backed by the given array.

Parameters:

a - an array.

size - the number of elements to be included in the queue.

c - the comparator used in this queue, or null for the natural order.

DoubleArrayPriorityQueue

public DoubleArrayPriorityQueue(double[] a,
 DoubleComparator c)

Wraps a given array in a queue using a given comparator.

The queue returned by this method will be backed by the given array.

Parameters:

a - an array.

c - the comparator used in this queue, or null for the natural order.

DoubleArrayPriorityQueue

public DoubleArrayPriorityQueue(double[] a,
 int size)

Wraps a given array in a queue using the natural order.

The queue returned by this method will be backed by the given array.

Parameters:

a - an array.

size - the number of elements to be included in the queue.

DoubleArrayPriorityQueue

public DoubleArrayPriorityQueue(double[] a)

Wraps a given array in a queue using the natural order.

The queue returned by this method will be backed by the given array.

Parameters:

a - an array.

Method Details

enqueue

public void enqueue(double x)

Description copied from interface: DoublePriorityQueue

Enqueues a new element.

Specified by:

enqueue in interface DoublePriorityQueue

Parameters:

x - the element to enqueue.

See Also:

• PriorityQueue.enqueue(Object)

dequeueDouble

public double dequeueDouble()

Description copied from interface: DoublePriorityQueue

Dequeues the first element from the queue.

Specified by:

dequeueDouble in interface DoublePriorityQueue

Returns:

the dequeued element.

See Also:

• DoublePriorityQueue.dequeue()

firstDouble

public double firstDouble()

Description copied from interface: DoublePriorityQueue

Returns the first element of the queue.

Specified by:

firstDouble in interface DoublePriorityQueue

Returns:

the first element.

See Also:

• DoublePriorityQueue.first()

changed

public void changed()

Description copied from interface: PriorityQueue

Notifies the queue that the first element has changed (optional operation).

This default implementation just throws an UnsupportedOperationException.

Specified by:

changed in interface PriorityQueue<Double>

size

public int size()

Description copied from interface: PriorityQueue

Returns the number of elements in this queue.

Specified by:

size in interface PriorityQueue<Double>

Returns:

the number of elements in this queue.

clear

public void clear()

Description copied from interface: PriorityQueue

Removes all elements from this queue.

Specified by:

clear in interface PriorityQueue<Double>

trim

public void trim()

Trims the underlying array so that it has exactly size() elements.

comparator

public DoubleComparator comparator()

Description copied from interface: DoublePriorityQueue

Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.

Specified by:

comparator in interface DoublePriorityQueue

Specified by:

comparator in interface PriorityQueue<Double>

Returns:

the comparator associated with this priority queue.

See Also:

• PriorityQueue.comparator()