Package it.unimi.dsi.fastutil.doubles

Class DoubleHeapPriorityQueue

java.lang.Object

it.unimi.dsi.fastutil.doubles.DoubleHeapPriorityQueue

All Implemented Interfaces:

DoublePriorityQueue, PriorityQueue<Double>, Serializable

public class DoubleHeapPriorityQueue
extends Object
implements DoublePriorityQueue, Serializable

A type-specific heap-based priority queue.

Instances of this class represent a priority queue using a heap. The heap is enlarged as needed, but it is never shrunk. Use the trim() method to reduce its size, if necessary.

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
DoubleHeapPriorityQueue()	Creates a new empty queue using the natural order.
DoubleHeapPriorityQueue(double[] a)	Wraps a given array in a queue using the natural order.
DoubleHeapPriorityQueue(double[] a, int size)	Wraps a given array in a queue using the natural order.
DoubleHeapPriorityQueue(double[] a, int size, DoubleComparator c)	Wraps a given array in a queue using a given comparator.
DoubleHeapPriorityQueue(double[] a, DoubleComparator c)	Wraps a given array in a queue using a given comparator.
DoubleHeapPriorityQueue(int capacity)	Creates a new empty queue with a given capacity and using the natural order.
DoubleHeapPriorityQueue(int capacity, DoubleComparator c)	Creates a new empty queue with a given capacity and comparator.
DoubleHeapPriorityQueue(DoubleCollection collection)	Creates a queue using the elements in a type-specific collection using the natural order.
DoubleHeapPriorityQueue(DoubleCollection collection, DoubleComparator c)	Creates a queue using the elements in a type-specific collection using a given comparator.
DoubleHeapPriorityQueue(DoubleComparator c)	Creates a new empty queue with a given comparator.
DoubleHeapPriorityQueue(Collection<? extends Double> collection)	Creates a queue using the elements in a collection using the natural order.
DoubleHeapPriorityQueue(Collection<? extends Double> collection, DoubleComparator c)	Creates a queue using the elements in a collection using 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 heap 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

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(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.

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(int capacity)

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

Parameters:

capacity - the initial capacity of this queue.

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(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.

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue()

Creates a new empty queue using the natural order.

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(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. The first size element of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of a one by one).

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.

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(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. The elements of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of a one by one).

Parameters:

a - an array.

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

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(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. The first size element of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of a one by one).

Parameters:

a - an array.

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

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(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. The elements of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of a one by one).

Parameters:

a - an array.

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(DoubleCollection collection,
 DoubleComparator c)

Creates a queue using the elements in a type-specific collection using a given comparator.

This constructor is more efficient than enqueing the elements of collection one by one.

Parameters:

collection - a collection; its elements will be used to initialize the queue.

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

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(DoubleCollection collection)

Creates a queue using the elements in a type-specific collection using the natural order.

This constructor is more efficient than enqueing the elements of collection one by one.

Parameters:

collection - a collection; its elements will be used to initialize the queue.

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(Collection<? extends Double> collection,
 DoubleComparator c)

Creates a queue using the elements in a collection using a given comparator.

This constructor is more efficient than enqueing the elements of collection one by one.

Parameters:

collection - a collection; its elements will be used to initialize the queue.

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

DoubleHeapPriorityQueue

public DoubleHeapPriorityQueue(Collection<? extends Double> collection)

Creates a queue using the elements in a collection using the natural order.

This constructor is more efficient than enqueing the elements of collection one by one.

Parameters:

collection - a collection; its elements will be used to initialize the queue.

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 heap 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()