Class DaryArrayHeap<K>
- Type Parameters:
K
- the type of keys maintained by this heap
- All Implemented Interfaces:
Serializable
,Heap<K>
Comparator
provided at heap creation time, depending on which
constructor is used.
The implementation uses an array in order to store the elements and
automatically maintains the size of the array much like a
Vector
does, providing amortized O(log_d(n)) time cost for
the insert
and amortized O(d log_d(n)) for the deleteMin
operation. Operation findMin
, is a worst-case O(1) operation. The
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.
Constructing such a heap from an array of elements can be performed using the
method heapify(int, Object[])
or
heapify(int, Object[], Comparator)
in linear time.
Note that the ordering maintained by a d-ary heap, like any heap, and whether
or not an explicit comparator is provided, must be consistent with
equals
if this heap is to correctly implement the Heap
interface. (See Comparable
or Comparator
for a precise
definition of consistent with equals.) This is so because the
Heap
interface is defined in terms of the equals
operation,
but a d-ary heap performs all key comparisons using its compareTo
(or
compare
) method, so two keys that are deemed equal by this method
are, from the standpoint of the d-ary heap, equal. The behavior of a heap
is well-defined even if its ordering is inconsistent with
equals
; it just fails to obey the general contract of the
Heap
interface.
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:
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected int
Degreestatic final int
Default initial capacity of the heap.private static final long
Fields inherited from class org.jheaps.array.AbstractArrayWeakHeap
array, comparator, DOWNSIZING_MIN_HEAP_CAPACITY, MAX_HEAP_CAPACITY, MIN_HEAP_CAPACITY, minCapacity, size
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Constructor Summary
ConstructorsConstructorDescriptionDaryArrayHeap
(int d) Constructs a new, empty heap, using the natural ordering of its keys.DaryArrayHeap
(int d, int capacity) Constructs a new, empty heap, with a provided initial capacity using the natural ordering of its keys.DaryArrayHeap
(int d, Comparator<? super K> comparator) Constructs a new, empty heap, ordered according to the given comparator.DaryArrayHeap
(int d, Comparator<? super K> comparator, int capacity) Constructs a new, empty heap, with a provided initial capacity ordered according to the given comparator. -
Method Summary
Modifier and TypeMethodDescriptionprotected void
ensureCapacity
(int capacity) Ensure that the array representation has the necessary capacity.protected void
fixdown
(int k) Downwards fix starting from a particular elementprotected void
fixdownWithComparator
(int k) Downwards fix starting from a particular element.protected void
fixup
(int k) Upwards fix starting from a particular elementprotected void
fixupWithComparator
(int k) Upwards fix starting from a particular element.static <K> DaryArrayHeap<K>
heapify
(int d, K[] array) Create a heap from an array of elements.static <K> DaryArrayHeap<K>
heapify
(int d, K[] array, Comparator<? super K> comparator) Create a heap from an array of elements.Methods inherited from class org.jheaps.array.AbstractArrayHeap
deleteMin, findMin, initCapacity, insert
Methods inherited from class org.jheaps.array.AbstractArrayWeakHeap
checkCapacity, clear, comparator, isEmpty, size
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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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d
protected int dDegree
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Constructor Details
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DaryArrayHeap
public DaryArrayHeap(int d) Constructs a new, empty heap, using the natural ordering of its keys.All keys inserted into the heap must implement the
Comparable
interface. Furthermore, all such keys must be mutually comparable:k1.compareTo(k2)
must not throw aClassCastException
for any keysk1
andk2
in the heap. If the user attempts to put a key into the heap that violates this constraint (for example, the user attempts to put a string key into a heap whose keys are integers), theinsert(Object key)
call will throw aClassCastException
.The initial capacity of the heap is
DEFAULT_HEAP_CAPACITY
and adjusts automatically based on the sequence of insertions and deletions.- Parameters:
d
- the number of children of each node in the d-ary heap- Throws:
IllegalArgumentException
- in case the number of children per node are less than 2
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DaryArrayHeap
public DaryArrayHeap(int d, int capacity) Constructs a new, empty heap, with a provided initial capacity using the natural ordering of its keys.All keys inserted into the heap must implement the
Comparable
interface. Furthermore, all such keys must be mutually comparable:k1.compareTo(k2)
must not throw aClassCastException
for any keysk1
andk2
in the heap. If the user attempts to put a key into the heap that violates this constraint (for example, the user attempts to put a string key into a heap whose keys are integers), theinsert(Object key)
call will throw aClassCastException
.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:
d
- the number of children of each node in the d-ary heapcapacity
- the initial heap capacity- Throws:
IllegalArgumentException
- in case the number of children per node are less than 2
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DaryArrayHeap
Constructs a new, empty heap, ordered according to the given comparator.All keys inserted into the heap must be mutually comparable by the given comparator:
comparator.compare(k1, k2)
must not throw aClassCastException
for any keysk1
andk2
in the heap. If the user attempts to put a key into the heap that violates this constraint, theinsert(Object key)
call will throw aClassCastException
.The initial capacity of the heap is
DEFAULT_HEAP_CAPACITY
and adjusts automatically based on the sequence of insertions and deletions.- Parameters:
d
- the number of children of each node in the d-ary heapcomparator
- the comparator that will be used to order this heap. Ifnull
, the natural ordering of the keys will be used.- Throws:
IllegalArgumentException
- in case the number of children per node are less than 2
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DaryArrayHeap
Constructs a new, empty heap, with a provided initial capacity ordered according to the given comparator.All keys inserted into the heap must be mutually comparable by the given comparator:
comparator.compare(k1, k2)
must not throw aClassCastException
for any keysk1
andk2
in the heap. If the user attempts to put a key into the heap that violates this constraint, theinsert(Object key)
call will throw aClassCastException
.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:
d
- the number of children of each node in the d-ary heapcomparator
- the comparator that will be used to order this heap. Ifnull
, the natural ordering of the keys will be used.capacity
- the initial heap capacity- Throws:
IllegalArgumentException
- in case the number of children per node are less than 2
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Method Details
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heapify
Create a heap from an array of elements. The elements of the array are not destroyed. The method has linear time complexity.- Type Parameters:
K
- the type of keys maintained by the heap- Parameters:
d
- the number of children of the d-ary heaparray
- an array of elements- Returns:
- a d-ary heap
- Throws:
IllegalArgumentException
- in case the number of children per node are less than 2IllegalArgumentException
- in case the array is null
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heapify
Create a heap from an array of elements. The elements of the array are not destroyed. The method has linear time complexity.- Type Parameters:
K
- the type of keys maintained by the heap- Parameters:
d
- the number of children of the d-ary heaparray
- an array of elementscomparator
- the comparator to use- Returns:
- a d-ary heap
- Throws:
IllegalArgumentException
- in case the number of children per node are less than 2IllegalArgumentException
- in case the array is null
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ensureCapacity
protected void ensureCapacity(int capacity) Ensure that the array representation has the necessary capacity.- Specified by:
ensureCapacity
in classAbstractArrayWeakHeap<K>
- Parameters:
capacity
- the requested capacity
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fixup
protected void fixup(int k) Description copied from class:AbstractArrayWeakHeap
Upwards fix starting from a particular element- Specified by:
fixup
in classAbstractArrayWeakHeap<K>
- Parameters:
k
- the index of the starting element
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fixupWithComparator
protected void fixupWithComparator(int k) Description copied from class:AbstractArrayWeakHeap
Upwards fix starting from a particular element. Performs comparisons using the comparator.- Specified by:
fixupWithComparator
in classAbstractArrayWeakHeap<K>
- Parameters:
k
- the index of the starting element
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fixdown
protected void fixdown(int k) Description copied from class:AbstractArrayWeakHeap
Downwards fix starting from a particular element- Specified by:
fixdown
in classAbstractArrayWeakHeap<K>
- Parameters:
k
- the index of the starting element
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fixdownWithComparator
protected void fixdownWithComparator(int k) Description copied from class:AbstractArrayWeakHeap
Downwards fix starting from a particular element. Performs comparisons using the comparator.- Specified by:
fixdownWithComparator
in classAbstractArrayWeakHeap<K>
- Parameters:
k
- the index of the starting element
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