Class ReflectedHeap<K,V>
- java.lang.Object
-
- org.jheaps.tree.ReflectedHeap<K,V>
-
- Type Parameters:
K
- the type of keys maintained by this heapV
- the type of values maintained by this heap
- All Implemented Interfaces:
java.io.Serializable
,AddressableHeap<K,V>
,DoubleEndedAddressableHeap<K,V>
,MergeableDoubleEndedAddressableHeap<K,V>
- Direct Known Subclasses:
ReflectedFibonacciHeap
,ReflectedPairingHeap
public class ReflectedHeap<K,V> extends java.lang.Object implements MergeableDoubleEndedAddressableHeap<K,V>, java.io.Serializable
Reflected double ended heaps. 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.This class implements a general technique which uses two
MergeableAddressableHeap
s to implement a double ended heap, described in detail in the following paper:- C. Makris, A. Tsakalidis, and K. Tsichlas. Reflected min-max heaps. Information Processing Letters, 86(4), 209--214, 2003.
The running time bounds depend on the implementation of the underlying used heap. All the above bounds, however, assume that the user does not perform cascading melds on heaps such as:
d.meld(e); c.meld(d); b.meld(c); a.meld(b);
The above scenario, although efficiently supported by using union-find with path compression, invalidates the claimed bounds.Note that the ordering maintained by a this 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 theAddressableHeap
interface. (SeeComparable
orComparator
for a precise definition of consistent with equals.) This is so because theAddressableHeap
interface is defined in terms of theequals
operation, but this heap performs all key comparisons using itscompareTo
(orcompare
) method, so two keys that are deemed equal by this method are, from the standpoint of this 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 theAddressableHeap
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:
- Serialized Form
-
-
Nested Class Summary
Nested Classes Modifier and Type Class Description private static class
ReflectedHeap.HandleMap<K,V>
private static class
ReflectedHeap.ReflectedHandle<K,V>
-
Nested classes/interfaces inherited from interface org.jheaps.DoubleEndedAddressableHeap
DoubleEndedAddressableHeap.Handle<K,V>
-
-
Field Summary
Fields Modifier and Type Field Description private java.util.Comparator<? super K>
comparator
The comparator used to maintain order in this heap, or null if it uses the natural ordering of its keys.private ReflectedHeap.ReflectedHandle<K,V>
free
A free element in case the size is oddprivate AddressableHeap<K,ReflectedHeap.HandleMap<K,V>>
maxHeap
A maximum heapprivate AddressableHeap<K,ReflectedHeap.HandleMap<K,V>>
minHeap
A minimum heapprivate ReflectedHeap<K,V>
other
Used to reference the current heap or some other heap in case of melding, so that handles remain valid even after a meld, without having to iterate over them.private static long
serialVersionUID
private long
size
Size of the heap
-
Constructor Summary
Constructors Constructor Description ReflectedHeap(AddressableHeapFactory<K,?> heapFactory)
Constructs a new, empty heap, using the natural ordering of its keys.ReflectedHeap(AddressableHeapFactory<K,?> heapFactory, java.util.Comparator<? super K> comparator)
Constructs a new, empty heap, ordered according to the given comparator.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
clear()
Clear all the elements of the heap.java.util.Comparator<? super K>
comparator()
Returns the comparator used to order the keys in this AddressableHeap, ornull
if this heap uses the natural ordering of its keys.private void
decreaseKey(ReflectedHeap.ReflectedHandle<K,V> n, K newKey)
Decrease the key of an element.private void
delete(ReflectedHeap.ReflectedHandle<K,V> n)
Delete an elementDoubleEndedAddressableHeap.Handle<K,V>
deleteMax()
Delete and return an element with the maximum key.DoubleEndedAddressableHeap.Handle<K,V>
deleteMin()
Delete and return an element with the minimum key.DoubleEndedAddressableHeap.Handle<K,V>
findMax()
Find an element with the maximum key.DoubleEndedAddressableHeap.Handle<K,V>
findMin()
Find an element with the minimum key.private void
increaseKey(ReflectedHeap.ReflectedHandle<K,V> n, K newKey)
Increase the key of an element.DoubleEndedAddressableHeap.Handle<K,V>
insert(K key)
Insert a new element into the heap with a null value.DoubleEndedAddressableHeap.Handle<K,V>
insert(K key, V value)
Insert a new element into the heap.private void
insertPair(ReflectedHeap.ReflectedHandle<K,V> handle1, ReflectedHeap.ReflectedHandle<K,V> handle2)
Insert a pair of elements, one in the min heap and one in the max heap.boolean
isEmpty()
Returnstrue
if this heap is empty.void
meld(MergeableDoubleEndedAddressableHeap<K,V> other)
Meld a heap into the current heap.long
size()
Returns the number of elements in the heap.
-
-
-
Field Detail
-
serialVersionUID
private static final long serialVersionUID
- See Also:
- Constant Field Values
-
comparator
private final java.util.Comparator<? super K> comparator
The comparator used to maintain order in this heap, or null if it uses the natural ordering of its keys.
-
minHeap
private final AddressableHeap<K,ReflectedHeap.HandleMap<K,V>> minHeap
A minimum heap
-
maxHeap
private final AddressableHeap<K,ReflectedHeap.HandleMap<K,V>> maxHeap
A maximum heap
-
free
private ReflectedHeap.ReflectedHandle<K,V> free
A free element in case the size is odd
-
size
private long size
Size of the heap
-
other
private ReflectedHeap<K,V> other
Used to reference the current heap or some other heap in case of melding, so that handles remain valid even after a meld, without having to iterate over them. In order to avoid maintaining a full-fledged union-find data structure, we disallow a heap to be used in melding more than once. We use however, path-compression in case of cascading melds, that it, a handle moves from one heap to another and then another.
-
-
Constructor Detail
-
ReflectedHeap
public ReflectedHeap(AddressableHeapFactory<K,?> heapFactory)
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:
heapFactory
- a factory for the underlying heap implementation- Throws:
java.lang.NullPointerException
- if the heap factory is null
-
ReflectedHeap
public ReflectedHeap(AddressableHeapFactory<K,?> heapFactory, java.util.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:
heapFactory
- a factory for the underlying heap implementationcomparator
- the comparator that will be used to order this heap. Ifnull
, the natural ordering of the keys will be used.- Throws:
java.lang.NullPointerException
- if the heap factory is null
-
-
Method Detail
-
comparator
public java.util.Comparator<? super K> comparator()
Returns the comparator used to order the keys in this AddressableHeap, ornull
if this heap uses the natural ordering of its keys.- Specified by:
comparator
in interfaceAddressableHeap<K,V>
- Returns:
- the comparator used to order the keys in this heap, or
null
if this addressable heap uses the natural ordering of its keys
-
isEmpty
public boolean isEmpty()
Returnstrue
if this heap is empty.- Specified by:
isEmpty
in interfaceAddressableHeap<K,V>
- Returns:
true
if this heap is empty,false
otherwise
-
size
public long size()
Returns the number of elements in the heap.- Specified by:
size
in interfaceAddressableHeap<K,V>
- Returns:
- the number of elements in the heap
-
clear
public void clear()
Clear all the elements of the heap. After calling this method all handles should be considered invalidated and the behavior of methodsAddressableHeap.Handle.decreaseKey(Object)
andAddressableHeap.Handle.delete()
is undefined.- Specified by:
clear
in interfaceAddressableHeap<K,V>
-
insert
public DoubleEndedAddressableHeap.Handle<K,V> insert(K key, V value)
Insert a new element into the heap.- Specified by:
insert
in interfaceAddressableHeap<K,V>
- Specified by:
insert
in interfaceDoubleEndedAddressableHeap<K,V>
- Parameters:
key
- the element's keyvalue
- the element's value- Returns:
- a handle for the newly added element
-
insert
public DoubleEndedAddressableHeap.Handle<K,V> insert(K key)
Insert a new element into the heap with a null value.- Specified by:
insert
in interfaceAddressableHeap<K,V>
- Specified by:
insert
in interfaceDoubleEndedAddressableHeap<K,V>
- Parameters:
key
- the element's key- Returns:
- a handle for the newly added element
-
findMin
public DoubleEndedAddressableHeap.Handle<K,V> findMin()
Find an element with the minimum key.- Specified by:
findMin
in interfaceAddressableHeap<K,V>
- Specified by:
findMin
in interfaceDoubleEndedAddressableHeap<K,V>
- Returns:
- a handle to an element with minimum key
-
findMax
public DoubleEndedAddressableHeap.Handle<K,V> findMax()
Find an element with the maximum key.- Specified by:
findMax
in interfaceDoubleEndedAddressableHeap<K,V>
- Returns:
- an element with the maximum key
-
deleteMin
public DoubleEndedAddressableHeap.Handle<K,V> deleteMin()
Delete and return an element with the minimum key. If multiple such elements exists, only one of them will be deleted. After the element is deleted the handle is invalidated and only methodAddressableHeap.Handle.getKey()
andAddressableHeap.Handle.getValue()
can be used.- Specified by:
deleteMin
in interfaceAddressableHeap<K,V>
- Specified by:
deleteMin
in interfaceDoubleEndedAddressableHeap<K,V>
- Returns:
- a handle to the deleted element with minimum key
-
deleteMax
public DoubleEndedAddressableHeap.Handle<K,V> deleteMax()
Delete and return an element with the maximum key. If multiple such elements exists, only one of them will be deleted.- Specified by:
deleteMax
in interfaceDoubleEndedAddressableHeap<K,V>
- Returns:
- the deleted element with the maximum key
-
meld
public void meld(MergeableDoubleEndedAddressableHeap<K,V> 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 interfaceMergeableDoubleEndedAddressableHeap<K,V>
- Parameters:
other
- a merge-able heap
-
insertPair
private void insertPair(ReflectedHeap.ReflectedHandle<K,V> handle1, ReflectedHeap.ReflectedHandle<K,V> handle2)
Insert a pair of elements, one in the min heap and one in the max heap.- Parameters:
handle1
- a handle to the first elementhandle2
- a handle to the second element
-
delete
private void delete(ReflectedHeap.ReflectedHandle<K,V> n)
Delete an element- Parameters:
n
- a handle to the element
-
decreaseKey
private void decreaseKey(ReflectedHeap.ReflectedHandle<K,V> n, K newKey)
Decrease the key of an element.- Parameters:
n
- the elementnewKey
- the new key
-
increaseKey
private void increaseKey(ReflectedHeap.ReflectedHandle<K,V> n, K newKey)
Increase the key of an element.- Parameters:
n
- the elementnewKey
- the new key
-
-