Class GabowStrongConnectivityInspector<V,​E>

  • Type Parameters:
    V - the graph vertex type
    E - the graph edge type
    All Implemented Interfaces:
    StrongConnectivityAlgorithm<V,​E>

    public class GabowStrongConnectivityInspector<V,​E>
    extends java.lang.Object
    Computes the strongly connected components of a directed graph. The implemented algorithm follows Cheriyan-Mehlhorn/Gabow's algorithm presented in Path-based depth-first search for strong and biconnected components by Gabow (2000). The running time is order of $O(|V|+|E|)$.
    Author:
    Sarah Komla-Ebri, Hannes Wellmann
    • Field Detail

      • graph

        protected final Graph<V,​E> graph
      • stronglyConnectedSets

        protected java.util.List<java.util.Set<V>> stronglyConnectedSets
      • stronglyConnectedSubgraphs

        protected java.util.List<Graph<V,​E>> stronglyConnectedSubgraphs
    • Constructor Detail

      • GabowStrongConnectivityInspector

        public GabowStrongConnectivityInspector​(Graph<V,​E> graph)
        Constructor
        Parameters:
        graph - the graph to inspect
        Throws:
        java.lang.NullPointerException - in case the graph is null
    • Method Detail

      • stronglyConnectedSets

        public java.util.List<java.util.Set<V>> stronglyConnectedSets()
        Description copied from interface: StrongConnectivityAlgorithm
        Computes a List of Sets, where each set contains vertices which together form a strongly connected component within the given graph.
        Returns:
        List of Set s containing the strongly connected components
      • getStronglyConnectedComponents

        public java.util.List<Graph<V,​E>> getStronglyConnectedComponents()
        Description copied from interface: StrongConnectivityAlgorithm
        Computes a list of subgraphs of the given graph. Each subgraph will represent a strongly connected component and will contain all vertices of that component. The subgraph will have an edge $(u,v)$ iff $u$ and $v$ are contained in the strongly connected component.
        Specified by:
        getStronglyConnectedComponents in interface StrongConnectivityAlgorithm<V,​E>
        Returns:
        a list of subgraphs representing the strongly connected components
      • getCondensation

        public Graph<Graph<V,​E>,​DefaultEdge> getCondensation()
        Description copied from interface: StrongConnectivityAlgorithm
        Compute the condensation of the given graph. If each strongly connected component is contracted to a single vertex, the resulting graph is a directed acyclic graph, the condensation of the graph.
        Specified by:
        getCondensation in interface StrongConnectivityAlgorithm<V,​E>
        Returns:
        the condensation of the given graph