Class BinaryArrayIntegerValueHeap<V>
- Type Parameters:
V
- the type of values maintained by this heap
- All Implemented Interfaces:
Serializable
,Heap<Integer>
,ValueHeap<Integer,
V>
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.
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Nested Class Summary
Nested Classes -
Field Summary
FieldsModifier and TypeFieldDescriptionprivate BinaryArrayIntegerValueHeap.Elem<V>[]
The array used for representing the heap.static final int
Default initial capacity of the heap.private static final int
Infimumprivate static final int
The maximum heap capacity.private static final int
The minimum heap capacity.private int
Minimum capacity due to initially requested capacity.private static final long
private int
Number of elements in the heap.private static final int
Supremum -
Constructor Summary
ConstructorsConstructorDescriptionConstructs 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
Modifier and TypeMethodDescriptionprivate void
checkCapacity
(int capacity) Check that a capacity is valid.void
clear()
Clear all the elements of this heap.Comparator
<? super Integer> Returns the comparator used to order the keys in this heap, ornull
if this heap uses the natural ordering of its keys.Delete and return an element with the minimum key.private void
ensureCapacity
(int capacity) Ensure that the array representation has the necessary capacity.findMin()
Find an element with the minimum key.Find the value of an element with the minimum key.void
Insert a key into the heap.void
Insert an element into the heap.boolean
isEmpty()
Returnstrue
if this heap is empty.long
size()
Returns the number of elements in this heap.
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Field Details
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serialVersionUID
private static final long serialVersionUID- See Also:
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DEFAULT_HEAP_CAPACITY
public static final int DEFAULT_HEAP_CAPACITYDefault initial capacity of the heap.- See Also:
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SUP_KEY
private static final int SUP_KEYSupremum- See Also:
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INF_KEY
private static final int INF_KEYInfimum- See Also:
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MAX_HEAP_CAPACITY
private static final int MAX_HEAP_CAPACITYThe maximum heap capacity.- See Also:
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MIN_HEAP_CAPACITY
private static final int MIN_HEAP_CAPACITYThe minimum heap capacity.- See Also:
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array
The array used for representing the heap. -
size
private int sizeNumber of elements in the heap. -
minCapacity
private int minCapacityMinimum capacity due to initially requested capacity.
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Constructor Details
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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
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Method Details
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isEmpty
public boolean isEmpty()Returnstrue
if this heap is empty. -
size
public long size()Returns the number of elements in this heap. -
clear
public void clear()Clear all the elements of this heap. -
comparator
Returns the comparator used to order the keys in this heap, ornull
if this heap uses the natural ordering of its keys.- Specified by:
comparator
in interfaceHeap<V>
- Returns:
- the comparator used to order the keys in this heap, or
null
if this heap uses the natural ordering of its keys
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findMin
Find an element with the minimum key. -
findMinValue
Find the value of an element with the minimum key.- Specified by:
findMinValue
in interfaceValueHeap<Integer,
V> - Returns:
- the value of an element with the minimum key
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insert
Insert an element into the heap. -
insert
Insert a key into the heap. -
deleteMin
Delete and return an element with the minimum key. If multiple such elements exists, only one of them will be deleted. -
ensureCapacity
private void ensureCapacity(int capacity) Ensure that the array representation has the necessary capacity.- Parameters:
capacity
- the requested capacity
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checkCapacity
private void checkCapacity(int capacity) Check that a capacity is valid.- Parameters:
capacity
- the capacity- Throws:
IllegalArgumentException
- if the capacity is negative or more than the maximum array size
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