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java.lang.Objectit.unimi.dsi.fastutil.AbstractIndirectPriorityQueue<java.lang.Long>
it.unimi.dsi.fastutil.longs.LongArrayIndirectPriorityQueue
public class LongArrayIndirectPriorityQueue
A type-specific array-based semi-indirect priority queue.
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.
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.
Constructor Summary | |
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LongArrayIndirectPriorityQueue(long[] refArray)
Creates a new empty queue with capacity equal to the length of the reference array and using the natural order. |
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LongArrayIndirectPriorityQueue(long[] refArray,
int capacity)
Creates a new empty queue with given capacity and using the natural order. |
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LongArrayIndirectPriorityQueue(long[] refArray,
int[] a)
Wraps a given array in a queue using the natural order. |
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LongArrayIndirectPriorityQueue(long[] refArray,
int[] a,
int size)
Wraps a given array in a queue using the natural order. |
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LongArrayIndirectPriorityQueue(long[] refArray,
int[] a,
int size,
LongComparator c)
Wraps a given array in a queue using a given comparator. |
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LongArrayIndirectPriorityQueue(long[] refArray,
int[] a,
LongComparator c)
Wraps a given array in a queue using a given comparator. |
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LongArrayIndirectPriorityQueue(long[] refArray,
int capacity,
LongComparator c)
Creates a new empty queue without elements with a given capacity and comparator. |
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LongArrayIndirectPriorityQueue(long[] refArray,
LongComparator c)
Creates a new empty queue with capacity equal to the length of the reference array and a given comparator. |
Method Summary | |
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void |
allChanged()
Notifies the queue that the all elements have changed (optional operation). |
void |
changed()
Notifies the queue that the first element has changed (optional operation). |
void |
changed(int index)
Notifies the queue that the specified element has changed (optional operation). Note that for efficiency reasons this method will not throw an exception when index is not in the queue. |
void |
clear()
Removes all elements from this queue. |
LongComparator |
comparator()
Returns the comparator associated with this queue, or null if it uses its elements' natural ordering. |
int |
dequeue()
Dequeues an element. |
void |
enqueue(int x)
Enqueues a new element. |
int |
first()
Returns the first element of the queue. |
int |
front(int[] a)
Retrieves the front of the queue in a given array (optional operation). |
int |
last()
Returns the last element of the queue, that is, the element the would be dequeued last (optional operation). |
void |
remove(int index)
Removes the specified element from the queue (optional operation). |
int |
size()
Returns the number of elements in this queue. |
java.lang.String |
toString()
|
void |
trim()
Trims the backing array so that it has exactly size() elements. |
Methods inherited from class it.unimi.dsi.fastutil.AbstractIndirectPriorityQueue |
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isEmpty |
Methods inherited from class java.lang.Object |
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equals, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public LongArrayIndirectPriorityQueue(long[] refArray, int capacity, LongComparator c)
refArray
- the reference array.capacity
- the initial capacity of this queue.c
- the comparator used in this queue, or null
for the natural order.public LongArrayIndirectPriorityQueue(long[] refArray, int capacity)
refArray
- the reference array.capacity
- the initial capacity of this queue.public LongArrayIndirectPriorityQueue(long[] refArray, LongComparator c)
refArray
- the reference array.c
- the comparator used in this queue, or null
for the natural order.public LongArrayIndirectPriorityQueue(long[] refArray)
refArray
- the reference array.public LongArrayIndirectPriorityQueue(long[] refArray, int[] a, int size, LongComparator c)
The queue returned by this method will be backed by the given array.
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.public LongArrayIndirectPriorityQueue(long[] refArray, int[] a, LongComparator c)
The queue returned by this method will be backed by the given array.
refArray
- the reference array.a
- an array of indices into refArray
.c
- the comparator used in this queue, or null
for the natural order.public LongArrayIndirectPriorityQueue(long[] refArray, int[] a, int size)
The queue returned by this method will be backed by the given array.
refArray
- the reference array.a
- an array of indices into refArray
.size
- the number of elements to be included in the queue.public LongArrayIndirectPriorityQueue(long[] refArray, int[] a)
The queue returned by this method will be backed by the given array.
refArray
- the reference array.a
- an array of indices into refArray
.Method Detail |
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public void enqueue(int x)
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.
x
- the element to enqueue..public int dequeue()
Note that each call to this method requires a complete scan of the backing array. Please consider caching its result.
public int first()
IndirectPriorityQueue
public int last()
IndirectPriorityQueue
last
in interface IndirectPriorityQueue<java.lang.Long>
last
in class AbstractIndirectPriorityQueue<java.lang.Long>
public void changed()
IndirectPriorityQueue
changed
in interface IndirectPriorityQueue<java.lang.Long>
changed
in class AbstractIndirectPriorityQueue<java.lang.Long>
public void changed(int index)
Note that the specified element must belong to the queue.
Note that for efficiency reasons this method will not throw an exception
when index
is not in the queue.
changed
in interface IndirectPriorityQueue<java.lang.Long>
changed
in class AbstractIndirectPriorityQueue<java.lang.Long>
index
- the element that has changed.public void allChanged()
IndirectPriorityQueue
allChanged
in interface IndirectPriorityQueue<java.lang.Long>
allChanged
in class AbstractIndirectPriorityQueue<java.lang.Long>
public void remove(int index)
IndirectPriorityQueue
Note that the specified element must belong to the queue.
remove
in interface IndirectPriorityQueue<java.lang.Long>
remove
in class AbstractIndirectPriorityQueue<java.lang.Long>
index
- the element to be removed.public int front(int[] a)
IndirectPriorityQueue
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 the queue.
a
- an array large enough to hold the front (e.g., at least long as the reference array).
a
).public int size()
IndirectPriorityQueue
public void clear()
IndirectPriorityQueue
public void trim()
size()
elements.
public LongComparator comparator()
IndirectPriorityQueue
null
if it uses its elements' natural ordering.
null
if it uses its elements' natural ordering.public java.lang.String toString()
toString
in class java.lang.Object
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