Package it.unimi.dsi.fastutil.objects

Class ObjectHeapPriorityQueue<K>

java.lang.Object
it.unimi.dsi.fastutil.objects.ObjectHeapPriorityQueue<K>
All Implemented Interfaces:
PriorityQueue<K>, Serializable
public class ObjectHeapPriorityQueue<K> extends Object implements PriorityQueue<K>, Serializable
A type-specific heap-based priority queue.

Instances of this class represent a priority queue using a heap. The heap is enlarged as needed, but it is never shrunk. Use the trim() method to reduce its size, if necessary.

See Also:

  • Constructor Details

    • ObjectHeapPriorityQueue

      public ObjectHeapPriorityQueue(int capacity, Comparator<? super K> 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.

    • ObjectHeapPriorityQueue

      public ObjectHeapPriorityQueue(int capacity)
      Creates a new empty queue with a given capacity and using the natural order.
      Parameters:
      capacity - the initial capacity of this queue.

    • ObjectHeapPriorityQueue

      public ObjectHeapPriorityQueue(Comparator<? super K> c)
      Creates a new empty queue with a given comparator.
      Parameters:
      c - the comparator used in this queue, or null for the natural order.

    • ObjectHeapPriorityQueue

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

    • ObjectHeapPriorityQueue

      public ObjectHeapPriorityQueue(K[] a, int size, Comparator<? super K> 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. The first size element of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of a one by one).

      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.

    • ObjectHeapPriorityQueue

      public ObjectHeapPriorityQueue(K[] a, Comparator<? super K> 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. The elements of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of a one by one).

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

    • ObjectHeapPriorityQueue

      public ObjectHeapPriorityQueue(K[] 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. The first size element of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of a one by one).

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

    • ObjectHeapPriorityQueue

      public ObjectHeapPriorityQueue(K[] 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. The elements of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of a one by one).

      Parameters:
      a - an array.

    • ObjectHeapPriorityQueue

      public ObjectHeapPriorityQueue(Collection<? extends K> collection, Comparator<? super K> c)
      Creates a queue using the elements in a collection using a given comparator.

      This constructor is more efficient than enqueing the elements of collection one by one.

      Parameters:
      collection - a collection; its elements will be used to initialize the queue.
      c - the comparator used in this queue, or null for the natural order.

    • ObjectHeapPriorityQueue

      public ObjectHeapPriorityQueue(Collection<? extends K> collection)
      Creates a queue using the elements in a collection using the natural order.

      This constructor is more efficient than enqueing the elements of collection one by one.

      Parameters:
      collection - a collection; its elements will be used to initialize the queue.

  • Method Details

    • enqueue

      public void enqueue(K x)
      Description copied from interface: PriorityQueue
      Enqueues a new element.
      Specified by:
      enqueue in interface PriorityQueue<K>
      Parameters:
      x - the element to enqueue.

    • dequeue

      public K dequeue()
      Description copied from interface: PriorityQueue
      Dequeues the first element from the queue.
      Specified by:
      dequeue in interface PriorityQueue<K>
      Returns:
      the dequeued element.

    • first

      public K first()
      Description copied from interface: PriorityQueue
      Returns the first element of the queue.
      Specified by:
      first in interface PriorityQueue<K>
      Returns:
      the first element.

    • changed

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

      This default implementation just throws an UnsupportedOperationException.

      Specified by:
      changed in interface PriorityQueue<K>

    • size

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

    • clear

      public void clear()
      Description copied from interface: PriorityQueue
      Removes all elements from this queue.
      Specified by:
      clear in interface PriorityQueue<K>

    • trim

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

    • comparator

      public Comparator<? super K> comparator()
      Description copied from interface: PriorityQueue
      Returns the comparator associated with this queue, or null if it uses its elements' natural ordering.
      Specified by:
      comparator in interface PriorityQueue<K>
      Returns:
      the comparator associated with this sorted set, or null if it uses its elements' natural ordering.