it.unimi.dsi.fastutil.shorts
Class ShortHeapSemiIndirectPriorityQueue

java.lang.Object
  it.unimi.dsi.fastutil.AbstractIndirectPriorityQueue<Short>
      it.unimi.dsi.fastutil.shorts.ShortHeapSemiIndirectPriorityQueue

All Implemented Interfaces:

IndirectPriorityQueue<Short>, ShortIndirectPriorityQueue

Direct Known Subclasses:

ShortHeapIndirectPriorityQueue

public class ShortHeapSemiIndirectPriorityQueue
extends AbstractIndirectPriorityQueue<Short>
implements ShortIndirectPriorityQueue

A type-specific heap-based semi-indirect priority queue.

Instances of this class use as reference list a reference array, which must be provided to each constructor. The priority queue is represented using a heap. The heap is enlarged as needed, but it is never shrunk. Use the trim() method to reduce its size, if necessary.

This implementation allows one to enqueue several time the same index, but you must be careful when calling changed().

Constructor Summary

ShortHeapSemiIndirectPriorityQueue(short[] refArray)
Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.

ShortHeapSemiIndirectPriorityQueue(short[] refArray, int capacity)
Creates a new empty queue with given capacity and using the natural order.

ShortHeapSemiIndirectPriorityQueue(short[] refArray, int[] a)
Wraps a given array in a queue using the natural order.

ShortHeapSemiIndirectPriorityQueue(short[] refArray, int[] a, int size)
Wraps a given array in a queue using the natural order.

ShortHeapSemiIndirectPriorityQueue(short[] refArray, int[] a, int size, ShortComparator c)
Wraps a given array in a queue using a given comparator.

ShortHeapSemiIndirectPriorityQueue(short[] refArray, int[] a, ShortComparator c)
Wraps a given array in a queue using a given comparator.

ShortHeapSemiIndirectPriorityQueue(short[] refArray, int capacity, ShortComparator c)
Creates a new empty queue without elements with a given capacity and comparator.

ShortHeapSemiIndirectPriorityQueue(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

void	allChanged() Rebuilds this heap in a bottom-up fashion.
void	changed() Notifies this queue that the first element has changed (optional operation).
void	clear() Removes all elements from this queue.
ShortComparator	comparator() Returns the comparator associated with this queue.
int	dequeue() Dequeues the first element from this queue.
void	enqueue(int x) Enqueues a new element.
int	first() Returns the first element of this queue.
int	front(int[] a) Retrieves the front of this queue in a given array (optional operation).
int	size() Returns the number of elements in this queue.
String	toString()
void	trim() Trims the backing array so that it has exactly size() elements.

Methods inherited from class it.unimi.dsi.fastutil.AbstractIndirectPriorityQueue

changed, contains, isEmpty, last, remove

Methods inherited from class java.lang.Object

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

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

changed, contains, isEmpty, last, remove

Constructor Detail

ShortHeapSemiIndirectPriorityQueue

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

Creates a new empty queue without elements 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.

ShortHeapSemiIndirectPriorityQueue

public ShortHeapSemiIndirectPriorityQueue(short[] refArray,
                                          int capacity)

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

Parameters:

refArray - the reference array.

capacity - the initial capacity of this queue.

ShortHeapSemiIndirectPriorityQueue

public ShortHeapSemiIndirectPriorityQueue(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.

ShortHeapSemiIndirectPriorityQueue

public ShortHeapSemiIndirectPriorityQueue(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.

ShortHeapSemiIndirectPriorityQueue

public ShortHeapSemiIndirectPriorityQueue(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.

ShortHeapSemiIndirectPriorityQueue

public ShortHeapSemiIndirectPriorityQueue(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.

ShortHeapSemiIndirectPriorityQueue

public ShortHeapSemiIndirectPriorityQueue(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.

ShortHeapSemiIndirectPriorityQueue

public ShortHeapSemiIndirectPriorityQueue(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 Detail

enqueue

public void enqueue(int x)

Description copied from interface: IndirectPriorityQueue

Enqueues a new element.

Specified by:

enqueue in interface IndirectPriorityQueue<Short>

Parameters:

x - the element to enqueue..

dequeue

public int dequeue()

Description copied from interface: IndirectPriorityQueue

Dequeues the first element from this queue.

Specified by:

dequeue in interface IndirectPriorityQueue<Short>

Returns:

the dequeued element.

first

public int first()

Description copied from interface: IndirectPriorityQueue

Returns the first element of this queue.

Specified by:

first in interface IndirectPriorityQueue<Short>

Returns:

the first element.

changed

public void changed()

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

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 AbstractIndirectPriorityQueue<Short>

allChanged

public void allChanged()

Rebuilds this heap in a bottom-up fashion.

Specified by:

allChanged in interface IndirectPriorityQueue<Short>

Overrides:

allChanged in class AbstractIndirectPriorityQueue<Short>

size

public int size()

Description copied from interface: IndirectPriorityQueue

Returns the number of elements in this queue.

Specified by:

size in interface IndirectPriorityQueue<Short>

Returns:

the number of elements in this queue.

clear

public void clear()

Description copied from interface: IndirectPriorityQueue

Removes all elements from this queue.

Specified by:

clear in interface IndirectPriorityQueue<Short>

trim

public void trim()

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

comparator

public ShortComparator comparator()

Description copied from interface: ShortIndirectPriorityQueue

Returns the comparator associated with this queue. Note that this specification strengthens the one given in IndirectPriorityQueue.

Specified by:

comparator in interface IndirectPriorityQueue<Short>

Specified by:

comparator in interface ShortIndirectPriorityQueue

Returns:

the comparator associated with this queue.

See Also:

IndirectPriorityQueue.comparator()

front

public int front(int[] a)

Description copied from interface: IndirectPriorityQueue

Retrieves the front of this queue in a given array (optional operation).

The front of an indirect queue is the set of indices whose associated elements in the reference array are equal to the element associated to the first index. These indices can be always obtain by dequeueing, but this method should retrieve efficiently such indices in the given array without modifying the state of this queue.

Specified by:

front in interface IndirectPriorityQueue<Short>

Parameters:

a - an array large enough to hold the front (e.g., at least long as the reference array).

Returns:

the number of elements actually written (starting from the first position of a).

toString

public String toString()

Overrides:

toString in class Object