it.unimi.dsi.fastutil.ints
Class IntArrayPriorityQueue

java.lang.Object
  extended by it.unimi.dsi.fastutil.AbstractPriorityQueue<Integer>
      extended by it.unimi.dsi.fastutil.ints.AbstractIntPriorityQueue
          extended by it.unimi.dsi.fastutil.ints.IntArrayPriorityQueue
All Implemented Interfaces:
IntPriorityQueue, PriorityQueue<Integer>

public class IntArrayPriorityQueue
extends AbstractIntPriorityQueue

A type-specific array-based priority queue.

Instances of this class represent a priority queue using a backing array—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.


Field Summary
protected  int[] array
          The backing array.
protected  IntComparator c
          The type-specific comparator used in this queue.
protected  int size
          The number of elements in this queue.
 
Constructor Summary
IntArrayPriorityQueue()
          Creates a new empty queue using the natural order.
IntArrayPriorityQueue(int capacity)
          Creates a new empty queue with a given capacity and using the natural order.
IntArrayPriorityQueue(int[] a)
          Wraps a given array in a queue using the natural order.
IntArrayPriorityQueue(int[] a, int size)
          Wraps a given array in a queue using the natural order.
IntArrayPriorityQueue(int[] a, IntComparator c)
          Wraps a given array in a queue using a given comparator.
IntArrayPriorityQueue(int[] a, int size, IntComparator c)
          Wraps a given array in a queue using a given comparator.
IntArrayPriorityQueue(IntComparator c)
          Creates a new empty queue with a given comparator.
IntArrayPriorityQueue(int capacity, IntComparator c)
          Creates a new empty queue with a given capacity and comparator.
 
Method Summary
 void changed()
          Notifies the queue that the first element has changed (optional operation).
 void clear()
          Removes all elements from this queue.
 IntComparator comparator()
          Returns the comparator associated with this sorted set, or null if it uses its elements' natural ordering.
 int dequeueInt()
          Dequeues an element.
 void enqueue(int x)
          Enqueues a new element.
 int firstInt()
          Returns the first element of the queue.
 int size()
          Returns the number of elements in this queue.
 void trim()
          Trims the underlying array so that it has exactly size() elements.
 
Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractIntPriorityQueue
dequeue, enqueue, first, last, lastInt
 
Methods inherited from class it.unimi.dsi.fastutil.AbstractPriorityQueue
isEmpty
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface it.unimi.dsi.fastutil.PriorityQueue
isEmpty
 

Field Detail

array

protected int[] array
The backing array.


size

protected int size
The number of elements in this queue.


c

protected IntComparator c
The type-specific comparator used in this queue.

Constructor Detail

IntArrayPriorityQueue

public IntArrayPriorityQueue(int capacity,
                             IntComparator c)
Creates a new empty queue with a given capacity and comparator.

Parameters:
capacity - the initial capacity of this queue.
c - the comparator used in this queue, or null for the natural order.

IntArrayPriorityQueue

public IntArrayPriorityQueue(int capacity)
Creates a new empty queue with a given capacity and using the natural order.

Parameters:
capacity - the initial capacity of this queue.

IntArrayPriorityQueue

public IntArrayPriorityQueue(IntComparator c)
Creates a new empty queue with a given comparator.

Parameters:
c - the comparator used in this queue, or null for the natural order.

IntArrayPriorityQueue

public IntArrayPriorityQueue()
Creates a new empty queue using the natural order.


IntArrayPriorityQueue

public IntArrayPriorityQueue(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.

Parameters:
a - an array.
size - the number of elements to be included in the queue.
c - the comparator used in this queue, or null for the natural order.

IntArrayPriorityQueue

public IntArrayPriorityQueue(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.

Parameters:
a - an array.
c - the comparator used in this queue, or null for the natural order.

IntArrayPriorityQueue

public IntArrayPriorityQueue(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:
a - an array.
size - the number of elements to be included in the queue.

IntArrayPriorityQueue

public IntArrayPriorityQueue(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:
a - an array.
Method Detail

enqueue

public void enqueue(int x)
Description copied from interface: IntPriorityQueue
Enqueues a new element.

Parameters:
x - the element to enqueue.

dequeueInt

public int dequeueInt()
Dequeues an element.

Note that each call to this method requires a complete scan of the backing array. Please consider caching its result.

Returns:
the dequeued element.

firstInt

public int firstInt()
Description copied from interface: IntPriorityQueue
Returns the first element of the queue.

Returns:
the first element.

changed

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

Specified by:
changed in interface PriorityQueue<Integer>
Overrides:
changed in class AbstractPriorityQueue<Integer>

size

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

Returns:
the number of elements in this queue.

clear

public void clear()
Description copied from interface: PriorityQueue
Removes all elements from this queue.


trim

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


comparator

public IntComparator comparator()
Description copied from interface: IntPriorityQueue
Returns the comparator associated with this sorted set, or null if it uses its elements' natural ordering.

Note that this specification strengthens the one given in PriorityQueue.comparator().

Returns:
the comparator associated with this sorted set, or null if it uses its elements' natural ordering.
See Also:
PriorityQueue.comparator()


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