Module org.jgrapht.core
Package org.jgrapht.alg.shortestpath
Class SuurballeKDisjointShortestPaths<V,E>
- java.lang.Object
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- org.jgrapht.alg.shortestpath.SuurballeKDisjointShortestPaths<V,E>
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- Type Parameters:
V
- the graph vertex typeE
- the graph edge type
- All Implemented Interfaces:
KShortestPathAlgorithm<V,E>
public class SuurballeKDisjointShortestPaths<V,E> extends Object
An implementation of Suurballe algorithm for finding K edge-disjoint shortest paths. The algorithm determines the k disjoint shortest simple paths in increasing order of weight. Only directed simple graphs are allowed.The algorithm is running k sequential Dijkstra iterations to find the shortest path at each step. Hence, yielding a complexity of k*O(Dijkstra).
For further reference see Wikipedia page
- Suurballe, J. W.; Tarjan, R. E. (1984), A quick method for finding shortest pairs of disjoint paths.
- Author:
- Assaf Mizrachi
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Field Summary
Fields Modifier and Type Field Description protected Graph<V,E>
originalGraph
protected List<List<E>>
pathList
protected Graph<V,E>
workingGraph
Graph on which shortest paths are searched.
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Constructor Summary
Constructors Constructor Description SuurballeKDisjointShortestPaths(Graph<V,E> graph)
Creates a new instance of the algorithm.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected GraphPath<V,E>
calculateShortestPath(V startVertex, V endVertex)
Calculates the shortest paths for the current iteration.List<GraphPath<V,E>>
getPaths(V startVertex, V endVertex, int k)
Returns the $k$ shortest simple paths in increasing order of weight.protected void
transformGraph(List<E> previousPath)
Prepares the working graph for next iteration.
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Constructor Detail
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SuurballeKDisjointShortestPaths
public SuurballeKDisjointShortestPaths(Graph<V,E> graph)
Creates a new instance of the algorithm.- Parameters:
graph
- graph on which shortest paths are searched.- Throws:
IllegalArgumentException
- if the graph is null.IllegalArgumentException
- if the graph is undirected.IllegalArgumentException
- if the graph is not simple.
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Method Detail
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transformGraph
protected void transformGraph(List<E> previousPath)
Prepares the working graph for next iteration. To be called from the second iteration and on so implementation may assume a precedingcalculateShortestPath(V, V)
call.- Parameters:
previousPath
- the path found at the previous iteration.
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calculateShortestPath
protected GraphPath<V,E> calculateShortestPath(V startVertex, V endVertex)
Calculates the shortest paths for the current iteration. Path is not final; rather, it is intended to be used in a "post-production" phase (see resolvePaths method).- Parameters:
startVertex
- the start vertexendVertex
- the end vertex- Returns:
- the shortest path between start and end vertices.
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getPaths
public List<GraphPath<V,E>> getPaths(V startVertex, V endVertex, int k)
Returns the $k$ shortest simple paths in increasing order of weight.- Specified by:
getPaths
in interfaceKShortestPathAlgorithm<V,E>
- Parameters:
startVertex
- source vertex of the calculated paths.endVertex
- target vertex of the calculated paths.k
- the number of shortest paths to return- Returns:
- list of disjoint paths between the start vertex and the end vertex
- Throws:
IllegalArgumentException
- if the graph does not contain the startVertex or the endVertexIllegalArgumentException
- if the startVertex and the endVertex are the same verticesIllegalArgumentException
- if the startVertex or the endVertex is null
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