Package it.unimi.dsi.fastutil.shorts

Class ShortHeapIndirectPriorityQueue

java.lang.Object

it.unimi.dsi.fastutil.shorts.ShortHeapSemiIndirectPriorityQueue

it.unimi.dsi.fastutil.shorts.ShortHeapIndirectPriorityQueue

All Implemented Interfaces:

IndirectPriorityQueue<Short>, ShortIndirectPriorityQueue

public class ShortHeapIndirectPriorityQueue
extends ShortHeapSemiIndirectPriorityQueue

A type-specific heap-based indirect priority queue.

Instances of this class use an additional inversion array, of the same length of the reference array, to keep track of the heap position containing a given element of the reference array. The priority queue is represented using a heap. The heap is enlarged as needed, but it is never shrunk. Use the ShortHeapSemiIndirectPriorityQueue.trim() method to reduce its size, if necessary.

Implementation Specification:

This implementation does not allow one to enqueue several times the same index.

Constructor Summary

Constructors

Constructor	Description
ShortHeapIndirectPriorityQueue(short[] refArray)	Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.
ShortHeapIndirectPriorityQueue(short[] refArray, int capacity)	Creates a new empty queue with a given capacity and using the natural order.
ShortHeapIndirectPriorityQueue(short[] refArray, int[] a)	Wraps a given array in a queue using the natural order.
ShortHeapIndirectPriorityQueue(short[] refArray, int[] a, int size)	Wraps a given array in a queue using the natural order.
ShortHeapIndirectPriorityQueue(short[] refArray, int[] a, int size, ShortComparator c)	Wraps a given array in a queue using a given comparator.
ShortHeapIndirectPriorityQueue(short[] refArray, int[] a, ShortComparator c)	Wraps a given array in a queue using a given comparator.
ShortHeapIndirectPriorityQueue(short[] refArray, int capacity, ShortComparator c)	Creates a new empty queue with a given capacity and comparator.
ShortHeapIndirectPriorityQueue(short[] refArray, ShortComparator c)	Creates a new empty queue with capacity equal to the length of the reference array and a given comparator.

Method Summary

Modifier and Type	Method	Description
void	allChanged()	Rebuilds this queue in a bottom-up fashion (in linear time).
void	changed()	Notifies this queue that the first element has changed (optional operation).
void	changed(int index)	Notifies this queue that the specified element has changed (optional operation).
void	clear()	Removes all elements from this queue.
boolean	contains(int index)	Checks whether a given index belongs to this queue (optional operation).
int	dequeue()	Dequeues the first element from this queue.
void	enqueue(int x)	Enqueues a new element.
boolean	remove(int index)	Removes the specified element from this queue (optional operation).

Methods inherited from class it.unimi.dsi.fastutil.shorts.ShortHeapSemiIndirectPriorityQueue

comparator, first, front, size, toString, trim

Methods inherited from class java.lang.Object

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

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

isEmpty, last

Constructor Details

ShortHeapIndirectPriorityQueue

public ShortHeapIndirectPriorityQueue(short[] refArray,
 int capacity,
 ShortComparator c)

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

Parameters:

refArray - the reference array.

capacity - the initial capacity of this queue.

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

ShortHeapIndirectPriorityQueue

public ShortHeapIndirectPriorityQueue(short[] refArray,
 int capacity)

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

Parameters:

refArray - the reference array.

capacity - the initial capacity of this queue.

ShortHeapIndirectPriorityQueue

public ShortHeapIndirectPriorityQueue(short[] refArray,
 ShortComparator c)

Creates a new empty queue with capacity equal to the length of the reference array and a given comparator.

Parameters:

refArray - the reference array.

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

ShortHeapIndirectPriorityQueue

public ShortHeapIndirectPriorityQueue(short[] refArray)

Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.

Parameters:

refArray - the reference array.

ShortHeapIndirectPriorityQueue

public ShortHeapIndirectPriorityQueue(short[] refArray,
 int[] a,
 int size,
 ShortComparator 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:

refArray - the reference array.

a - an array of indices into refArray.

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

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

ShortHeapIndirectPriorityQueue

public ShortHeapIndirectPriorityQueue(short[] refArray,
 int[] a,
 ShortComparator 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:

refArray - the reference array.

a - an array of indices into refArray.

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

ShortHeapIndirectPriorityQueue

public ShortHeapIndirectPriorityQueue(short[] refArray,
 int[] 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:

refArray - the reference array.

a - an array of indices into refArray.

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

ShortHeapIndirectPriorityQueue

public ShortHeapIndirectPriorityQueue(short[] refArray,
 int[] 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:

refArray - the reference array.

a - an array of indices into refArray.

Method Details

enqueue

public void enqueue(int x)

Description copied from interface: IndirectPriorityQueue

Enqueues a new element.

Specified by:

enqueue in interface IndirectPriorityQueue<Short>

Overrides:

enqueue in class ShortHeapSemiIndirectPriorityQueue

Parameters:

x - the element to enqueue.

contains

public boolean contains(int index)

Description copied from interface: IndirectPriorityQueue

Checks whether a given index belongs to this queue (optional operation).

This default implementation just throws an UnsupportedOperationException.

Parameters:

index - an index possibly in the queue.

Returns:

true if the specified index belongs to this queue.

dequeue

public int dequeue()

Description copied from interface: IndirectPriorityQueue

Dequeues the first element from this queue.

Specified by:

dequeue in interface IndirectPriorityQueue<Short>

Overrides:

dequeue in class ShortHeapSemiIndirectPriorityQueue

Returns:

the dequeued element.

changed

public void changed()

Description copied from class: ShortHeapSemiIndirectPriorityQueue

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

This default implementation just calls IndirectPriorityQueue.changed(int) with argument IndirectPriorityQueue.first().

The caller must guarantee that when this method is called the index of the first element appears just once in the queue. Failure to do so will bring the queue in an inconsistent state, and will cause unpredictable behaviour.

Specified by:

changed in interface IndirectPriorityQueue<Short>

Overrides:

changed in class ShortHeapSemiIndirectPriorityQueue

changed

public void changed(int index)

Description copied from interface: IndirectPriorityQueue

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

Note that the specified element must belong to this queue.

This default implementation just throws an UnsupportedOperationException.

Parameters:

index - the element that has changed.

allChanged

public void allChanged()

Rebuilds this queue in a bottom-up fashion (in linear time).

Specified by:

allChanged in interface IndirectPriorityQueue<Short>

Overrides:

allChanged in class ShortHeapSemiIndirectPriorityQueue

remove

public boolean remove(int index)

Description copied from interface: IndirectPriorityQueue

Removes the specified element from this queue (optional operation).

This default implementation just throws an UnsupportedOperationException.

Parameters:

index - the element to be removed.

Returns:

true if the index was in the queue.

clear

public void clear()

Description copied from interface: IndirectPriorityQueue

Removes all elements from this queue.

Specified by:

clear in interface IndirectPriorityQueue<Short>

Overrides:

clear in class ShortHeapSemiIndirectPriorityQueue