org.jgrapht.alg.flow

Class EdmondsKarpMaximumFlow<V,E>

java.lang.Object

org.jgrapht.alg.flow.MaximumFlowAlgorithmBase<V,E>

org.jgrapht.alg.flow.EdmondsKarpMaximumFlow<V,E>

All Implemented Interfaces:

MaximumFlowAlgorithm<V,E>

public final class EdmondsKarpMaximumFlow<V,E>
extends MaximumFlowAlgorithmBase<V,E>

A flow network is a directed graph where each edge has a capacity and each edge receives a flow. The amount of flow on an edge can not exceed the capacity of the edge (note, that all capacities must be non-negative). A flow must satisfy the restriction that the amount of flow into a vertex equals the amount of flow out of it, except when it is a source, which "produces" flow, or sink, which "consumes" flow.

This class computes maximum flow in a network using Edmonds-Karp algorithm. Be careful: for large networks this algorithm may consume significant amount of time (its upper-bound complexity is O(VE^2), where V - amount of vertices, E - amount of edges in the network).

For more details see Andrew V. Goldberg's Combinatorial Optimization (Lecture Notes).

Author:

Ilya Razensteyn

Nested Class Summary

Nested classes/interfaces inherited from interface org.jgrapht.alg.interfaces.MaximumFlowAlgorithm

MaximumFlowAlgorithm.MaximumFlow<V,E>, MaximumFlowAlgorithm.MaximumFlowImpl<V,E>

Field Summary

Fields inherited from class org.jgrapht.alg.flow.MaximumFlowAlgorithmBase

DEFAULT_EPSILON

Constructor Summary

Constructors

Constructor and Description
EdmondsKarpMaximumFlow(DirectedGraph<V,E> network) Constructs MaximumFlow instance to work with a copy of network.
EdmondsKarpMaximumFlow(DirectedGraph<V,E> network, double epsilon) Constructs MaximumFlow instance to work with a copy of network.

Method Summary

Methods

Modifier and Type	Method and Description
MaximumFlowAlgorithm.MaximumFlow<V,E>	buildMaximumFlow(V source, V sink) Sets current source to source, current sink to sink, then calculates maximum flow from source to sink.
protected org.jgrapht.alg.flow.EdmondsKarpMaximumFlow.EdgeExtension	extendedEdge(E e)
protected org.jgrapht.alg.flow.EdmondsKarpMaximumFlow.VertexExtension	extendedVertex(V v)
V	getCurrentSink() Returns current sink vertex, or null if there was no calculateMaximumFlow calls.
V	getCurrentSource() Returns current source vertex, or null if there was no calculateMaximumFlow calls.

Methods inherited from class org.jgrapht.alg.flow.MaximumFlowAlgorithmBase

compareFlowTo, composeFlow, edgeExtended, pushFlowThrough, vertexExtended

Methods inherited from class java.lang.Object

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

Constructor Detail

EdmondsKarpMaximumFlow

public EdmondsKarpMaximumFlow(DirectedGraph<V,E> network)

Constructs MaximumFlow instance to work with a copy of network. Current source and sink are set to null. If network is weighted, then capacities are weights, otherwise all capacities are equal to one. Doubles are compared using DEFAULT_EPSILON tolerance.

Parameters:

network - network, where maximum flow will be calculated

EdmondsKarpMaximumFlow

public EdmondsKarpMaximumFlow(DirectedGraph<V,E> network,
                      double epsilon)

Constructs MaximumFlow instance to work with a copy of network. Current source and sink are set to null. If network is weighted, then capacities are weights, otherwise all capacities are equal to one.

Parameters:

network - network, where maximum flow will be calculated

epsilon - tolerance for comparing doubles

Method Detail

buildMaximumFlow

public MaximumFlowAlgorithm.MaximumFlow<V,E> buildMaximumFlow(V source,
                                                     V sink)

Sets current source to source, current sink to sink, then calculates maximum flow from source to sink. Note, that source and sink must be vertices of the network passed to the constructor, and they must be different.

Parameters:

source - source vertex

sink - sink vertex

Returns:

maximum flow

extendedVertex

protected org.jgrapht.alg.flow.EdmondsKarpMaximumFlow.VertexExtension extendedVertex(V v)

extendedEdge

protected org.jgrapht.alg.flow.EdmondsKarpMaximumFlow.EdgeExtension extendedEdge(E e)

getCurrentSource

public V getCurrentSource()

Returns current source vertex, or null if there was no calculateMaximumFlow calls.

Returns:

current source

getCurrentSink

public V getCurrentSink()

Returns current sink vertex, or null if there was no calculateMaximumFlow calls.

Returns:

current sink