Class BinaryTreeSoftHeap<K>
- java.lang.Object
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- org.jheaps.tree.BinaryTreeSoftHeap<K>
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- Type Parameters:
K
- the type of keys maintained by this heap
- All Implemented Interfaces:
Serializable
,Heap<K>
,MergeableHeap<K>
public class BinaryTreeSoftHeap<K> extends Object implements Heap<K>, MergeableHeap<K>, Serializable
A binary tree soft heap. The heap is sorted according to the natural ordering of its keys, or by aComparator
provided at heap creation time, depending on which constructor is used.If n elements are inserted into a soft heap, then up to εn of the elements still contained in the heap, for a given error parameter ε, may be corrupted, i.e., have their keys artificially increased. In exchange for allowing these corruptions, each soft heap operation is performed in O(log 1/ε) amortized time. Note that n here is the number of elements inserted into the heaps, not the current number of elements in the heap which may be considerably smaller. Moreover the user has no control on which elements may be corrupted.
This variant of the soft heap is due to Kaplan and Zwick, described in detail in the following paper:
- Haim Kaplan and Uri Zwick, A simpler implementation and analysis of Chazelle's Soft Heaps, In Proceedings of the 20th Annual ACM-SIAM Symposium on Discrete Algorithms (SODA 2009), 477--485, 2009.
Note that the ordering maintained by a soft 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 theHeap
interface. (SeeComparable
orComparator
for a precise definition of consistent with equals.) This is so because theHeap
interface is defined in terms of theequals
operation, but a pairing heap performs all key comparisons using itscompareTo
(orcompare
) method, so two keys that are deemed equal by this method are, from the standpoint of the heap, equal. The behavior of a heap is well-defined even if its ordering is inconsistent withequals
; it just fails to obey the general contract of theHeap
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.
- Author:
- Dimitrios Michail
- See Also:
- Serialized Form
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Constructor Summary
Constructors Constructor Description BinaryTreeSoftHeap(double errorRate)
Constructs a new, empty heap, using the natural ordering of its keys.BinaryTreeSoftHeap(double errorRate, Comparator<? super K> comparator)
Constructs a new, empty heap, ordered according to the given comparator.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
clear()
Clear all the elements of this heap.Comparator<? super K>
comparator()
Returns the comparator used to order the keys in this heap, ornull
if this heap uses the natural ordering of its keys.K
deleteMin()
Delete and return an element with the minimum key.K
findMin()
Find an element with the minimum key.void
insert(K key)
Insert a key into the heap.boolean
isEmpty()
Returnstrue
if this heap is empty.void
meld(MergeableHeap<K> other)
Meld a heap into the current heap.long
size()
Returns the number of elements in this heap.
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Constructor Detail
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BinaryTreeSoftHeap
public BinaryTreeSoftHeap(double errorRate)
Constructs a new, empty heap, using the natural ordering of its keys. All keys inserted into the heap must implement theComparable
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
.- Parameters:
errorRate
- the error rate- Throws:
IllegalArgumentException
- if the error rate is less or equal to zeroIllegalArgumentException
- if the error rate is greater or equal to one
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BinaryTreeSoftHeap
public BinaryTreeSoftHeap(double errorRate, Comparator<? super K> comparator)
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
.- Parameters:
errorRate
- the error ratecomparator
- the comparator that will be used to order this heap. Ifnull
, the natural ordering of the keys will be used.- Throws:
IllegalArgumentException
- if the error rate is less or equal to zeroIllegalArgumentException
- if the error rate is greater or equal to one
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Method Detail
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isEmpty
public boolean isEmpty()
Returnstrue
if this heap is empty.
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size
public long size()
Returns the number of elements in this heap.
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comparator
public Comparator<? super K> 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<K>
- 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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clear
public void clear()
Clear all the elements of this heap.
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meld
public void meld(MergeableHeap<K> other)
Meld a heap into the current heap. After the operation theother
heap will be empty and will not permit further insertions.- Specified by:
meld
in interfaceMergeableHeap<K>
- Parameters:
other
- a merge-able heap- Throws:
IllegalArgumentException
- ifother
has a different error rate
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insert
public void insert(K key)
Insert a key into the heap.
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findMin
public K findMin()
Find an element with the minimum key.
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