Module org.jhotdraw8.graph

Package org.jhotdraw8.graph.path.algo

Class UniqueShortestArcPathSearchAlgo<V,A,C extends Number & Comparable<C>>

java.lang.Object

org.jhotdraw8.graph.path.algo.UniqueShortestArcPathSearchAlgo<V,A,C>

Type Parameters:

V - the vertex data type

A - the arrow data type

C - the cost number type

All Implemented Interfaces:

ArcPathSearchAlgo<V,A,C>

public class UniqueShortestArcPathSearchAlgo<V,A,C extends Number & Comparable<C>>
extends Object
implements ArcPathSearchAlgo<V,A,C>

Searches a unique shortest path from a set of start vertices to a set of goal vertices using Dijkstra's algorithm.

If the graph is acyclic, then the provided cost function must return values >= 0 for all arrows.
If the graph has cycles, then the provided cost function must return values > 0 for all arrows. (If the graph has cycles and the cost function returns values that are 0, then this algorithm incorrectly considers a path as non-unique, if it can be reached by a walk).

Performance characteristics:

When the algorithm returns a back link

less or equal O( |A| + |V|*log|V| ) within max cost

When the algorithm returns null

less or equal O( |A| + |V|*log|V| ) within max cost

References:

Edsger W. Dijkstra (1959)

A note on two problems in connexion with graphs,Problem 2. tum.de

Sampath Kannan, Sanjeef Khanna, Sudeepa Roy. (2008)

STCON in Directed Unique-Path Graphs. Chapter 2.1 Properties of Unique-Path Graphs. cis.upenn.edu

Constructor Summary

Constructors

Constructor	Description
UniqueShortestArcPathSearchAlgo()

Method Summary

Modifier and Type	Method	Description
@Nullable ArcBackLinkWithCost<V,A,C>	search(@NonNull Iterable<V> startVertices, @NonNull Predicate<V> goalPredicate, @NonNull Function<V,Iterable<Arc<V,A>>> nextArcsFunction, int maxDepth, @NonNull C zero, @NonNull C costLimit, @NonNull Function3<V,V,A,C> costFunction, @NonNull BiFunction<C,C,C> sumFunction, @NonNull AddToSet<V> visited)	Search engine method.

Methods inherited from class java.lang.Object

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

Constructor Details

UniqueShortestArcPathSearchAlgo

public UniqueShortestArcPathSearchAlgo()

Method Details

search

public @Nullable ArcBackLinkWithCost<V,A,C> search(@NonNull Iterable<V> startVertices,
 @NonNull Predicate<V> goalPredicate,
 @NonNull Function<V,Iterable<Arc<V,A>>> nextArcsFunction,
 int maxDepth,
 @NonNull C zero,
 @NonNull C costLimit,
 @NonNull Function3<V,V,A,C> costFunction,
 @NonNull BiFunction<C,C,C> sumFunction,
 @NonNull AddToSet<V> visited)

Search engine method.

Specified by:

search in interface ArcPathSearchAlgo<V,A,C extends Number & Comparable<C>>

Parameters:

startVertices - the set of start vertices

goalPredicate - the goal predicate

nextArcsFunction - the next arcs function

maxDepth - the maximal depth (inclusive) of the search Must be >= 0.

zero - the zero cost value

costLimit - the maximal cost (inclusive) of a path. Must be >= zero.

costFunction - the cost function.
The cost must be > 0 if the graph has cycles.
The cost must be >= 0 if the graph is acyclic.

sumFunction - the sum function for adding two cost values

visited -

Returns:

on success: a back link, otherwise: null