Package it.unimi.dsi.fastutil.longs

Class LongArrayIndirectPriorityQueue

  • All Implemented Interfaces:
    IndirectPriorityQueue<Long>, LongIndirectPriorityQueue
    public class LongArrayIndirectPriorityQueue
extends Object
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.

    • Method Summary

      Modifier and Type Method Description
      void allChanged()
      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.
      LongComparator comparator()
      Returns the type-specific 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)
      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.
      String toString()  
      void trim()
      Trims the backing array so that it has exactly size() elements.

    • 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.