Package it.unimi.dsi.fastutil.floats

Class FloatArrayIndirectPriorityQueue

java.lang.Object
it.unimi.dsi.fastutil.floats.FloatArrayIndirectPriorityQueue
All Implemented Interfaces:
FloatIndirectPriorityQueue, it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>
public class FloatArrayIndirectPriorityQueue
extends java.lang.Object
implements FloatIndirectPriorityQueue
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.

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.

  • Constructor Summary

    Constructors
    Constructor Description
    FloatArrayIndirectPriorityQueue​(float[] refArray)
    Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.
    FloatArrayIndirectPriorityQueue​(float[] refArray, int capacity)
    Creates a new empty queue with given capacity and using the natural order.
    FloatArrayIndirectPriorityQueue​(float[] refArray, int[] a)
    Wraps a given array in a queue using the natural order.
    FloatArrayIndirectPriorityQueue​(float[] refArray, int[] a, int size)
    Wraps a given array in a queue using the natural order.
    FloatArrayIndirectPriorityQueue​(float[] refArray, int[] a, int size, FloatComparator c)
    Wraps a given array in a queue using a given comparator.
    FloatArrayIndirectPriorityQueue​(float[] refArray, int[] a, FloatComparator c)
    Wraps a given array in a queue using a given comparator.
    FloatArrayIndirectPriorityQueue​(float[] refArray, int capacity, FloatComparator c)
    Creates a new empty queue without elements with a given capacity and comparator.
    FloatArrayIndirectPriorityQueue​(float[] refArray, FloatComparator 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()
    Signals the queue that all elements have changed.
    void changed()  
    void changed​(int index)
    void clear()  
    FloatComparator comparator()
    Returns the type-specific comparator associated with this queue.
    int dequeue()  
    void enqueue​(int x)
    int first()  
    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()  
    boolean remove​(int index)  
    int size()  
    java.lang.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

    contains, isEmpty

  • Constructor Details

    • FloatArrayIndirectPriorityQueue

      public FloatArrayIndirectPriorityQueue​(float[] refArray, int capacity, FloatComparator 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.

    • FloatArrayIndirectPriorityQueue

      public FloatArrayIndirectPriorityQueue​(float[] 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.

    • FloatArrayIndirectPriorityQueue

      public FloatArrayIndirectPriorityQueue​(float[] refArray, FloatComparator 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.

    • FloatArrayIndirectPriorityQueue

      public FloatArrayIndirectPriorityQueue​(float[] 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.

    • FloatArrayIndirectPriorityQueue

      public FloatArrayIndirectPriorityQueue​(float[] refArray, int[] a, int size, FloatComparator 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.

    • FloatArrayIndirectPriorityQueue

      public FloatArrayIndirectPriorityQueue​(float[] refArray, int[] a, FloatComparator 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.

    • FloatArrayIndirectPriorityQueue

      public FloatArrayIndirectPriorityQueue​(float[] 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.

    • FloatArrayIndirectPriorityQueue

      public FloatArrayIndirectPriorityQueue​(float[] 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 Details

    • enqueue

      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.

      Specified by:
      enqueue in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • dequeue

      public int dequeue()
      Specified by:
      dequeue in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • first

      public int first()
      Specified by:
      first in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • last

      public int last()
      Specified by:
      last in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • changed

      public void changed()
      Specified by:
      changed in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • changed

      public void changed​(int index)

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

      Specified by:
      changed in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • allChanged

      public void allChanged()
      Signals the queue that all elements have changed.
      Specified by:
      allChanged in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • remove

      public boolean remove​(int index)
      Specified by:
      remove in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • 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 it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>
      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.

    • size

      public int size()
      Specified by:
      size in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • clear

      public void clear()
      Specified by:
      clear in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>

    • trim

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

    • comparator

      public FloatComparator comparator()
      Description copied from interface: FloatIndirectPriorityQueue
      Returns the type-specific comparator associated with this queue.
      Specified by:
      comparator in interface FloatIndirectPriorityQueue
      Specified by:
      comparator in interface it.unimi.dsi.fastutil.IndirectPriorityQueue<java.lang.Float>
      Returns:
      the comparator associated with this queue.
      See Also:
      IndirectPriorityQueue.comparator()

    • toString

      public java.lang.String toString()
      Overrides:
      toString in class java.lang.Object