Package it.unimi.dsi.fastutil.ints

Class IntHeapSemiIndirectPriorityQueue

java.lang.Object

it.unimi.dsi.fastutil.ints.IntHeapSemiIndirectPriorityQueue

All Implemented Interfaces:

IndirectPriorityQueue<Integer>, IntIndirectPriorityQueue

Direct Known Subclasses:

IntHeapIndirectPriorityQueue

public class IntHeapSemiIndirectPriorityQueue
extends Object
implements IntIndirectPriorityQueue

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.

Implementation Specification:

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

Constructor Summary

Constructors

Constructor	Description
IntHeapSemiIndirectPriorityQueue(int[] refArray)	Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.
IntHeapSemiIndirectPriorityQueue(int[] refArray, int capacity)	Creates a new empty queue with given capacity and using the natural order.
IntHeapSemiIndirectPriorityQueue(int[] refArray, int[] a)	Wraps a given array in a queue using the natural order.
IntHeapSemiIndirectPriorityQueue(int[] refArray, int[] a, int size)	Wraps a given array in a queue using the natural order.
IntHeapSemiIndirectPriorityQueue(int[] refArray, int[] a, int size, IntComparator c)	Wraps a given array in a queue using a given comparator.
IntHeapSemiIndirectPriorityQueue(int[] refArray, int[] a, IntComparator c)	Wraps a given array in a queue using a given comparator.
IntHeapSemiIndirectPriorityQueue(int[] refArray, int capacity, IntComparator c)	Creates a new empty queue without elements with a given capacity and comparator.
IntHeapSemiIndirectPriorityQueue(int[] refArray, IntComparator 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 heap in a bottom-up fashion (in linear time).
void	changed()	Notifies this queue that the first element has changed (optional operation).
void	clear()	Removes all elements from this queue.
IntComparator	comparator()	Returns the type-specific 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)	Writes in the provided array the front of the queue, that is, the set of indices whose elements have the same priority as the top.
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 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 Details

IntHeapSemiIndirectPriorityQueue

public IntHeapSemiIndirectPriorityQueue(int[] refArray,
 int capacity,
 IntComparator 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.

IntHeapSemiIndirectPriorityQueue

public IntHeapSemiIndirectPriorityQueue(int[] 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.

IntHeapSemiIndirectPriorityQueue

public IntHeapSemiIndirectPriorityQueue(int[] refArray,
 IntComparator 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.

IntHeapSemiIndirectPriorityQueue

public IntHeapSemiIndirectPriorityQueue(int[] 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.

IntHeapSemiIndirectPriorityQueue

public IntHeapSemiIndirectPriorityQueue(int[] refArray,
 int[] a,
 int size,
 IntComparator 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.

IntHeapSemiIndirectPriorityQueue

public IntHeapSemiIndirectPriorityQueue(int[] refArray,
 int[] a,
 IntComparator 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.

IntHeapSemiIndirectPriorityQueue

public IntHeapSemiIndirectPriorityQueue(int[] 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.

IntHeapSemiIndirectPriorityQueue

public IntHeapSemiIndirectPriorityQueue(int[] 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<Integer>

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<Integer>

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<Integer>

Returns:

the first element.

changed

public void changed()

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<Integer>

allChanged

public void allChanged()

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

Specified by:

allChanged in interface IndirectPriorityQueue<Integer>

size

public int size()

Description copied from interface: IndirectPriorityQueue

Returns the number of elements in this queue.

Specified by:

size in interface IndirectPriorityQueue<Integer>

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<Integer>

trim

public void trim()

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

comparator

public IntComparator comparator()

Description copied from interface: IntIndirectPriorityQueue

Returns the type-specific comparator associated with this queue.

Specified by:

comparator in interface IndirectPriorityQueue<Integer>

Specified by:

comparator in interface IntIndirectPriorityQueue

Returns:

the comparator associated with this queue.

See Also:

• IndirectPriorityQueue.comparator()

front

public int front(int[] a)

Writes in the provided array the front of the queue, that is, the set of indices whose elements have the same priority as the top.

Specified by:

front in interface IndirectPriorityQueue<Integer>

Parameters:

a - an array whose initial part will be filled with the frnot (must be sized as least as the heap size).

Returns:

the number of elements of the front.

toString

public String toString()

Overrides:

toString in class Object