ai.grakn.graql.internal.gremlin.spanningtree.datastructure

Class FibonacciHeap<V,P>

java.lang.Object

ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap<V,P>

Type Parameters:

V - the type of the values stored in the heap

P - the type of the priorities

All Implemented Interfaces:

Iterable<ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry>

public class FibonacciHeap<V,P>
extends Object
implements Iterable<ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry>

A Fibonacci heap (due to Fredman and Tarjan).

This implementation was inspired and informed by those of Nathan L. Fiedler (https://github.com/nlfiedler/graphmaker/blob/990227c766a9891be1d4669c582975f7c1a4db87/core/src/com/bluemarsh/graphmaker/core/util/FibonacciHeap.java), and Keith Schwarz (htiek@cs.stanford.edu) (http://www.keithschwarz.com/interesting/code/?dir=fibonacci-heap), but rewritten from scratch by Sam Thomson (sthomson@cs.cmu.edu).

Author:

Sam Thomson, Jason Liu

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_CAPACITY

Method Summary

Modifier and Type	Method and Description
Optional<ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry>	add(V value, P priority) Inserts a new entry into the heap and returns the entry if heap is not full.
void	clear() Removes all elements from the heap.
Comparator<? super P>	comparator() Returns the comparator used to order the elements in this queue.
static <T,C extends Comparable> FibonacciHeap<T,C>	create() Create a new FibonacciHeap based on the natural ordering on `C`
static <T,C> FibonacciHeap<T,C>	create(Comparator<? super C> comparator)
void	decreasePriority(ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry entry, P newPriority) Decreases the priority for an entry.
boolean	isEmpty() Returns true if the heap is empty, false otherwise.
Iterator<ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry>	iterator() Returns every entry in this heap, in no particular order.
static <U,P> FibonacciHeap<U,P>	merge(FibonacciHeap<U,P> a, FibonacciHeap<U,P> b) Joins two Fibonacci heaps into a new one.
Optional<ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry>	peekOption() Returns the entry with the minimum priority, or absent if empty.
Optional<V>	pollOption() Removes the smallest element from the heap.
void	remove(ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry entry) Deletes `entry` from the heap.
int	size() Returns the number of elements in the heap.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

MAX_CAPACITY

public static final int MAX_CAPACITY

See Also:

Constant Field Values

Method Detail

create

public static <T,C> FibonacciHeap<T,C> create(Comparator<? super C> comparator)

create

public static <T,C extends Comparable> FibonacciHeap<T,C> create()

Create a new FibonacciHeap based on the natural ordering on `C`

comparator

public Comparator<? super P> comparator()

Returns the comparator used to order the elements in this queue.

clear

public void clear()

Removes all elements from the heap. Runtime: O(1)

decreasePriority

public void decreasePriority(ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry entry,
                             P newPriority)

Decreases the priority for an entry. Runtime: O(1) (amortized)

remove

public void remove(ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry entry)

Deletes `entry` from the heap. The heap will be consolidated, if necessary. Runtime: O(log n) amortized

isEmpty

public boolean isEmpty()

Returns true if the heap is empty, false otherwise. Runtime: O(1)

add

public Optional<ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry> add(V value,
                                                                                                    P priority)

Inserts a new entry into the heap and returns the entry if heap is not full. Returns absent otherwise. No heap consolidation is performed. Runtime: O(1)

peekOption

public Optional<ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry> peekOption()

Returns the entry with the minimum priority, or absent if empty. Runtime: O(1)

pollOption

public Optional<V> pollOption()

Removes the smallest element from the heap. This will cause the trees in the heap to be consolidated, if necessary. Runtime: O(log n) amortized

size

public int size()

Returns the number of elements in the heap. Runtime: O(1)

merge

public static <U,P> FibonacciHeap<U,P> merge(FibonacciHeap<U,P> a,
                                             FibonacciHeap<U,P> b)

Joins two Fibonacci heaps into a new one. No heap consolidation is performed; the two root lists are just spliced together. Runtime: O(1)

iterator

public Iterator<ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry> iterator()

Returns every entry in this heap, in no particular order.

Specified by:

iterator in interface Iterable<ai.grakn.graql.internal.gremlin.spanningtree.datastructure.FibonacciHeap.Entry>