Class ObjectArrayIndirectPriorityQueue<K>
- All Implemented Interfaces:
IndirectPriorityQueue<K>
Instances of this class use as reference list a reference array, which must be provided
to each constructor, and represent a priority queue using a backing array of integer
indices—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.
- Implementation Specification:
- This implementation is extremely inefficient, but it is difficult to beat when the size of the queue is very small. Moreover, it allows to enqueue several time the same index, without limitations.
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Constructor Summary
ConstructorDescriptionObjectArrayIndirectPriorityQueue
(K[] refArray) Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.ObjectArrayIndirectPriorityQueue
(K[] refArray, int capacity) Creates a new empty queue with given capacity and using the natural order.ObjectArrayIndirectPriorityQueue
(K[] refArray, int[] a) Wraps a given array in a queue using the natural order.ObjectArrayIndirectPriorityQueue
(K[] refArray, int[] a, int size) Wraps a given array in a queue using the natural order.ObjectArrayIndirectPriorityQueue
(K[] refArray, int[] a, int size, Comparator<? super K> c) Wraps a given array in a queue using a given comparator.ObjectArrayIndirectPriorityQueue
(K[] refArray, int[] a, Comparator<? super K> c) Wraps a given array in a queue using a given comparator.ObjectArrayIndirectPriorityQueue
(K[] refArray, int capacity, Comparator<? super K> c) Creates a new empty queue without elements with a given capacity and comparator.ObjectArrayIndirectPriorityQueue
(K[] refArray, Comparator<? super K> c) Creates a new empty queue with capacity equal to the length of the reference array and a given comparator. -
Method Summary
Modifier and TypeMethodDescriptionvoid
Signals the queue that all elements have changed.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.Comparator
<? super K> Returns the comparator associated with this queue, ornull
if it uses its elements' natural ordering.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
last()
Returns the last element of this queue, that is, the element the would be dequeued last (optional operation).boolean
remove
(int index) Removes the specified element from this queue (optional operation).int
size()
Returns the number of elements in this queue.toString()
void
trim()
Trims the backing array so that it has exactlysize()
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
contains, isEmpty
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Constructor Details
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ObjectArrayIndirectPriorityQueue
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, ornull
for the natural order.
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ObjectArrayIndirectPriorityQueue
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.
-
ObjectArrayIndirectPriorityQueue
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, ornull
for the natural order.
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ObjectArrayIndirectPriorityQueue
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.
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ObjectArrayIndirectPriorityQueue
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:
refArray
- the reference array.a
- an array of indices intorefArray
.size
- the number of elements to be included in the queue.c
- the comparator used in this queue, ornull
for the natural order.
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ObjectArrayIndirectPriorityQueue
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:
refArray
- the reference array.a
- an array of indices intorefArray
.c
- the comparator used in this queue, ornull
for the natural order.
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ObjectArrayIndirectPriorityQueue
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:
refArray
- the reference array.a
- an array of indices intorefArray
.size
- the number of elements to be included in the queue.
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ObjectArrayIndirectPriorityQueue
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:
refArray
- the reference array.a
- an array of indices intorefArray
.
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Method Details
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enqueue
public void enqueue(int x) Enqueues a new element.Note that for efficiency reasons this method will not throw an exception when
x
is already in the queue. However, the queue state will become inconsistent and the following behaviour will not be predictable.- Specified by:
enqueue
in interfaceIndirectPriorityQueue<K>
- Parameters:
x
- the element to enqueue.
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dequeue
public int dequeue()Description copied from interface:IndirectPriorityQueue
Dequeues the first element from this queue.- Specified by:
dequeue
in interfaceIndirectPriorityQueue<K>
- Returns:
- the dequeued element.
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first
public int first()Description copied from interface:IndirectPriorityQueue
Returns the first element of this queue.- Specified by:
first
in interfaceIndirectPriorityQueue<K>
- Returns:
- the first element.
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last
public int last()Description copied from interface:IndirectPriorityQueue
Returns the last element of this queue, that is, the element the would be dequeued last (optional operation).This default implementation just throws an
UnsupportedOperationException
.- Specified by:
last
in interfaceIndirectPriorityQueue<K>
- Returns:
- the last element.
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changed
public void changed()Description copied from interface:IndirectPriorityQueue
Notifies this queue that the first element has changed (optional operation).This default implementation just calls
IndirectPriorityQueue.changed(int)
with argumentIndirectPriorityQueue.first()
.- Specified by:
changed
in interfaceIndirectPriorityQueue<K>
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changed
public void changed(int index) 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
.Note that for efficiency reasons this method will not throw an exception when
index
is not in the queue.- Specified by:
changed
in interfaceIndirectPriorityQueue<K>
- Parameters:
index
- the element that has changed.
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allChanged
public void allChanged()Signals the queue that all elements have changed.- Specified by:
allChanged
in interfaceIndirectPriorityQueue<K>
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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
.- Specified by:
remove
in interfaceIndirectPriorityQueue<K>
- Parameters:
index
- the element to be removed.- Returns:
- true if the index was in the queue.
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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 interfaceIndirectPriorityQueue<K>
- 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.
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size
public int size()Description copied from interface:IndirectPriorityQueue
Returns the number of elements in this queue.- Specified by:
size
in interfaceIndirectPriorityQueue<K>
- Returns:
- the number of elements in this queue.
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clear
public void clear()Description copied from interface:IndirectPriorityQueue
Removes all elements from this queue.- Specified by:
clear
in interfaceIndirectPriorityQueue<K>
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trim
public void trim()Trims the backing array so that it has exactlysize()
elements. -
comparator
Description copied from interface:IndirectPriorityQueue
Returns the comparator associated with this queue, ornull
if it uses its elements' natural ordering.- Specified by:
comparator
in interfaceIndirectPriorityQueue<K>
- Returns:
- the comparator associated with this sorted set, or
null
if it uses its elements' natural ordering.
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toString
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