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
    implements StrongConnectivityAlgorithm<V,​E>
    Allows obtaining 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|)
    Since:
    September, 2013
    • Constructor Detail

      • GabowStrongConnectivityInspector

        public GabowStrongConnectivityInspector​(DirectedGraph<V,​E> directedGraph)
        The constructor of GabowStrongConnectivityInspector class.
        Parameters:
        directedGraph - the graph to inspect
        Throws:
        java.lang.IllegalArgumentException - in case the graph is null
    • Method Detail

      • isStronglyConnected

        public boolean isStronglyConnected()
        Returns true if the graph instance is strongly connected.
        Specified by:
        isStronglyConnected in interface StrongConnectivityAlgorithm<V,​E>
        Returns:
        true if the graph is strongly connected, false otherwise
      • stronglyConnectedSets

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

        public java.util.List<DirectedSubgraph<V,​E>> stronglyConnectedSubgraphs()

        Computes a list of DirectedSubgraphs 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.

        NOTE: Calling this method will first execute stronglyConnectedSets(). If you don't need subgraphs, use that method.

        Specified by:
        stronglyConnectedSubgraphs in interface StrongConnectivityAlgorithm<V,​E>
        Returns:
        a list of subgraphs representing the strongly connected components
      • createVertexNumber

        private void createVertexNumber()