it.unimi.dsi.fastutil.longs
Class LongArrayIndirectPriorityQueue

java.lang.Object
  extended by it.unimi.dsi.fastutil.AbstractIndirectPriorityQueue<Long>
      extended by it.unimi.dsi.fastutil.longs.LongArrayIndirectPriorityQueue
All Implemented Interfaces:
IndirectPriorityQueue<Long>, LongIndirectPriorityQueue

public class LongArrayIndirectPriorityQueue
extends AbstractIndirectPriorityQueue<Long>
implements LongIndirectPriorityQueue

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
LongArrayIndirectPriorityQueue(long[] refArray)
          Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.
LongArrayIndirectPriorityQueue(long[] refArray, int capacity)
          Creates a new empty queue with given capacity and using the natural order.
LongArrayIndirectPriorityQueue(long[] refArray, int[] a)
          Wraps a given array in a queue using the natural order.
LongArrayIndirectPriorityQueue(long[] refArray, int[] a, int size)
          Wraps a given array in a queue using the natural order.
LongArrayIndirectPriorityQueue(long[] refArray, int[] a, int size, LongComparator c)
          Wraps a given array in a queue using a given comparator.
LongArrayIndirectPriorityQueue(long[] refArray, int[] a, LongComparator c)
          Wraps a given array in a queue using a given comparator.
LongArrayIndirectPriorityQueue(long[] refArray, int capacity, LongComparator c)
          Creates a new empty queue without elements with a given capacity and comparator.
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
 void allChanged()
          Notifies this queue that the all elements have changed (optional operation).
 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.
 LongComparator 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 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.
 String toString()
           
 void trim()
          Trims the backing array so that it has exactly size() elements.
 
Methods inherited from class it.unimi.dsi.fastutil.AbstractIndirectPriorityQueue
contains, isEmpty
 
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
 

Constructor Detail

LongArrayIndirectPriorityQueue

public LongArrayIndirectPriorityQueue(long[] refArray,
                                      int capacity,
                                      LongComparator 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.

LongArrayIndirectPriorityQueue

public LongArrayIndirectPriorityQueue(long[] 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.

LongArrayIndirectPriorityQueue

public LongArrayIndirectPriorityQueue(long[] refArray,
                                      LongComparator 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.

LongArrayIndirectPriorityQueue

public LongArrayIndirectPriorityQueue(long[] 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.

LongArrayIndirectPriorityQueue

public LongArrayIndirectPriorityQueue(long[] refArray,
                                      int[] a,
                                      int size,
                                      LongComparator 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.

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.

LongArrayIndirectPriorityQueue

public LongArrayIndirectPriorityQueue(long[] refArray,
                                      int[] a,
                                      LongComparator 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.

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.

LongArrayIndirectPriorityQueue

public LongArrayIndirectPriorityQueue(long[] 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.

Parameters:
refArray - the reference array.
a - an array of indices into refArray.
size - the number of elements to be included in the queue.

LongArrayIndirectPriorityQueue

public LongArrayIndirectPriorityQueue(long[] 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.

Parameters:
refArray - the reference array.
a - an array of indices into refArray.
Method Detail

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 interface IndirectPriorityQueue<Long>
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<Long>
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<Long>
Returns:
the first element.

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).

Specified by:
last in interface IndirectPriorityQueue<Long>
Overrides:
last in class AbstractIndirectPriorityQueue<Long>
Returns:
the last element.

changed

public void changed()
Description copied from interface: IndirectPriorityQueue
Notifies this queue that the first element has changed (optional operation).

Specified by:
changed in interface IndirectPriorityQueue<Long>
Overrides:
changed in class AbstractIndirectPriorityQueue<Long>

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.

Note that for efficiency reasons this method will not throw an exception when index is not in the queue.

Specified by:
changed in interface IndirectPriorityQueue<Long>
Overrides:
changed in class AbstractIndirectPriorityQueue<Long>
Parameters:
index - the element that has changed.

allChanged

public void allChanged()
Description copied from interface: IndirectPriorityQueue
Notifies this queue that the all elements have changed (optional operation).

Specified by:
allChanged in interface IndirectPriorityQueue<Long>
Overrides:
allChanged in class AbstractIndirectPriorityQueue<Long>

remove

public boolean remove(int index)
Description copied from interface: IndirectPriorityQueue
Removes the specified element from this queue (optional operation).

Specified by:
remove in interface IndirectPriorityQueue<Long>
Overrides:
remove in class AbstractIndirectPriorityQueue<Long>
Parameters:
index - the element to be removed.
Returns:
true if the index was in the queue.

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<Long>
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).

size

public int size()
Description copied from interface: IndirectPriorityQueue
Returns the number of elements in this queue.

Specified by:
size in interface IndirectPriorityQueue<Long>
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<Long>

trim

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


comparator

public LongComparator comparator()
Description copied from interface: LongIndirectPriorityQueue
Returns the comparator associated with this queue. Note that this specification strengthens the one given in IndirectPriorityQueue.

Specified by:
comparator in interface IndirectPriorityQueue<Long>
Specified by:
comparator in interface LongIndirectPriorityQueue
Returns:
the comparator associated with this queue.
See Also:
IndirectPriorityQueue.comparator()

toString

public String toString()
Overrides:
toString in class Object