Package it.unimi.dsi.fastutil.longs

Class LongArrayPriorityQueue

java.lang.Object

it.unimi.dsi.fastutil.longs.LongArrayPriorityQueue

All Implemented Interfaces:

LongPriorityQueue, PriorityQueue<java.lang.Long>, java.io.Serializable

public class LongArrayPriorityQueue
extends java.lang.Object
implements LongPriorityQueue, java.io.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
LongArrayPriorityQueue()	Creates a new empty queue using the natural order.
LongArrayPriorityQueue(int capacity)	Creates a new empty queue with a given capacity and using the natural order.
LongArrayPriorityQueue(int capacity, LongComparator c)	Creates a new empty queue with a given capacity and comparator.
LongArrayPriorityQueue(long[] a)	Wraps a given array in a queue using the natural order.
LongArrayPriorityQueue(long[] a, int size)	Wraps a given array in a queue using the natural order.
LongArrayPriorityQueue(long[] a, int size, LongComparator c)	Wraps a given array in a queue using a given comparator.
LongArrayPriorityQueue(long[] a, LongComparator c)	Wraps a given array in a queue using a given comparator.
LongArrayPriorityQueue(LongComparator 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.
LongComparator	comparator()	Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.
long	dequeueLong()	Dequeues the first element from the queue.
void	enqueue(long x)	Enqueues a new element.
long	firstLong()	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.longs.LongPriorityQueue

dequeue, enqueue, first, last, lastLong

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

isEmpty

Constructor Details

LongArrayPriorityQueue

public LongArrayPriorityQueue(int capacity,
LongComparator 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.

LongArrayPriorityQueue

public LongArrayPriorityQueue(int capacity)

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

Parameters:

capacity - the initial capacity of this queue.

LongArrayPriorityQueue

public LongArrayPriorityQueue(LongComparator c)

Creates a new empty queue with a given comparator.

Parameters:

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

LongArrayPriorityQueue

public LongArrayPriorityQueue()

Creates a new empty queue using the natural order.

LongArrayPriorityQueue

public LongArrayPriorityQueue(long[] a,
int size,
LongComparator 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.

LongArrayPriorityQueue

public LongArrayPriorityQueue(long[] a,
LongComparator 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.

LongArrayPriorityQueue

public LongArrayPriorityQueue(long[] 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.

LongArrayPriorityQueue

public LongArrayPriorityQueue(long[] 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(long x)

Description copied from interface: LongPriorityQueue

Enqueues a new element.

Specified by:

enqueue in interface LongPriorityQueue

Parameters:

x - the element to enqueue.

See Also:

PriorityQueue.enqueue(Object)

dequeueLong

public long dequeueLong()

Description copied from interface: LongPriorityQueue

Dequeues the first element from the queue.

Specified by:

dequeueLong in interface LongPriorityQueue

Returns:

the dequeued element.

See Also:

LongPriorityQueue.dequeue()

firstLong

public long firstLong()

Description copied from interface: LongPriorityQueue

Returns the first element of the queue.

Specified by:

firstLong in interface LongPriorityQueue

Returns:

the first element.

See Also:

LongPriorityQueue.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<java.lang.Long>

size

public int size()

Description copied from interface: PriorityQueue

Returns the number of elements in this queue.

Specified by:

size in interface PriorityQueue<java.lang.Long>

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<java.lang.Long>

trim

public void trim()

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

comparator

public LongComparator comparator()

Description copied from interface: LongPriorityQueue

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

Specified by:

comparator in interface LongPriorityQueue

Specified by:

comparator in interface PriorityQueue<java.lang.Long>

Returns:

the comparator associated with this priority queue.

See Also:

PriorityQueue.comparator()