Package org.jheaps.array

Class BinaryArrayIntegerValueHeap<V>

  • Type Parameters:
    V - the type of values maintained by this heap
    All Implemented Interfaces:
    java.io.Serializable, Heap<java.lang.Integer>, ValueHeap<java.lang.Integer,​V>
    public class BinaryArrayIntegerValueHeap<V>
extends java.lang.Object
implements ValueHeap<java.lang.Integer,​V>, java.io.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.

    See Also:
    Serialized Form

    • Constructor Summary

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

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      private void checkCapacity​(int capacity)
      Check that a capacity is valid.
      void clear()
      Clear all the elements of this heap.
      java.util.Comparator<? super java.lang.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.
      java.lang.Integer deleteMin()
      Delete and return an element with the minimum key.
      private void ensureCapacity​(int capacity)
      Ensure that the array representation has the necessary capacity.
      java.lang.Integer findMin()
      Find an element with the minimum key.
      V findMinValue()
      Find the value of an element with the minimum key.
      void insert​(java.lang.Integer key)
      Insert a key into the heap.
      void insert​(java.lang.Integer key, V value)
      Insert an element into the heap.
      boolean isEmpty()
      Returns true if this heap is empty.
      long size()
      Returns the number of elements in this heap.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • DEFAULT_HEAP_CAPACITY

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

      • MAX_HEAP_CAPACITY

        private static final int MAX_HEAP_CAPACITY
        The maximum heap capacity.
        See Also:
        Constant Field Values

      • MIN_HEAP_CAPACITY

        private static final int MIN_HEAP_CAPACITY
        The minimum heap capacity.
        See Also:
        Constant Field Values

      • size

        private int size
        Number of elements in the heap.

      • minCapacity

        private int minCapacity
        Minimum capacity due to initially requested capacity.

    • Constructor Detail

      • 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 Detail

      • 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 java.util.Comparator<? super java.lang.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 java.lang.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<java.lang.Integer,​V>
        Returns:
        the value of an element with the minimum key

      • insert

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

      • insert

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

      • deleteMin

        public java.lang.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

      • ensureCapacity

        private void ensureCapacity​(int capacity)
        Ensure that the array representation has the necessary capacity.
        Parameters:
        capacity - the requested capacity

      • checkCapacity

        private void checkCapacity​(int capacity)
        Check that a capacity is valid.
        Parameters:
        capacity - the capacity
        Throws:
        java.lang.IllegalArgumentException - if the capacity is negative or more than the maximum array size