Package org.jheaps.array

Class BinaryArrayIntegerValueHeap<V>

java.lang.Object
org.jheaps.array.BinaryArrayIntegerValueHeap<V>
Type Parameters:
V - the type of values maintained by this heap
All Implemented Interfaces:
Serializable, Heap<Integer>, ValueHeap<Integer,V>
public class BinaryArrayIntegerValueHeap<V> extends Object implements ValueHeap<Integer,V>, Serializable
An optimized array-based binary heap with integer keys.

This is a highly optimized implementation which uses (a) the Wegener bottom-up heuristic and (b) sentinel values. The implementation uses an array in order to store the elements, providing amortized O(log(n)) time for the insert and deleteMin operations. Operation findMin, is a worst-case O(1) operation. All bounds are worst-case if the user initializes the heap with a capacity larger or equal to the total number of elements that are going to be inserted into the heap.

See the following papers for details about the optimizations:

  • Ingo Wegener. BOTTOM-UP-HEAPSORT, a new variant of HEAPSORT beating, on an average, QUICKSORT (if n is not very small). Theoretical Computer Science, 118(1), 81--98, 1993.
  • Peter Sanders. Fast Priority Queues for Cached Memory. Algorithms Engineering and Experiments (ALENEX), 312--327, 1999.

Note that this implementation is not synchronized. If multiple threads access a heap concurrently, and at least one of the threads modifies the heap structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more elements or changing the key of some element.) This is typically accomplished by synchronizing on some object that naturally encapsulates the heap.

Author:
Dimitrios Michail
See Also:

  • Field Details

    • DEFAULT_HEAP_CAPACITY

      public static final int DEFAULT_HEAP_CAPACITY
      Default initial capacity of the heap.
      See Also:

  • Constructor Details

    • BinaryArrayIntegerValueHeap

      public BinaryArrayIntegerValueHeap()
      Constructs a new, empty heap, using the natural ordering of its keys.

      The initial capacity of the heap is DEFAULT_HEAP_CAPACITY and adjusts automatically based on the sequence of insertions and deletions.

    • BinaryArrayIntegerValueHeap

      public BinaryArrayIntegerValueHeap(int capacity)
      Constructs a new, empty heap, with a provided initial capacity using the natural ordering of its keys.

      The initial capacity of the heap is provided by the user and is adjusted automatically based on the sequence of insertions and deletions. The capacity will never become smaller than the initial requested capacity.

      Parameters:
      capacity - the initial heap capacity

  • Method Details

    • isEmpty

      public boolean isEmpty()
      Returns true if this heap is empty.
      Specified by:
      isEmpty in interface Heap<V>
      Returns:
      true if this heap is empty, false otherwise

    • size

      public long size()
      Returns the number of elements in this heap.
      Specified by:
      size in interface Heap<V>
      Returns:
      the number of elements in this heap

    • clear

      public void clear()
      Clear all the elements of this heap.
      Specified by:
      clear in interface Heap<V>

    • comparator

      public Comparator<? super Integer> comparator()
      Returns the comparator used to order the keys in this heap, or null if this heap uses the natural ordering of its keys.
      Specified by:
      comparator in interface Heap<V>
      Returns:
      the comparator used to order the keys in this heap, or null if this heap uses the natural ordering of its keys

    • findMin

      public Integer findMin()
      Find an element with the minimum key.
      Specified by:
      findMin in interface Heap<V>
      Returns:
      an element with the minimum key

    • findMinValue

      public V findMinValue()
      Find the value of an element with the minimum key.
      Specified by:
      findMinValue in interface ValueHeap<Integer,V>
      Returns:
      the value of an element with the minimum key

    • insert

      public void insert(Integer key, V value)
      Insert an element into the heap.
      Specified by:
      insert in interface ValueHeap<Integer,V>
      Parameters:
      key - the key to insert
      value - the value to insert

    • insert

      public void insert(Integer key)
      Insert a key into the heap.
      Specified by:
      insert in interface Heap<V>
      Parameters:
      key - the key to insert

    • deleteMin

      public Integer deleteMin()
      Delete and return an element with the minimum key. If multiple such elements exists, only one of them will be deleted.
      Specified by:
      deleteMin in interface Heap<V>
      Returns:
      the deleted element with the minimum key