Package org.jgrapht.alg.cycle

Class SzwarcfiterLauerSimpleCycles<V,​E>

  • Type Parameters:
    V - the vertex type.
    E - the edge type.
    All Implemented Interfaces:
    DirectedSimpleCycles<V,​E>
    public class SzwarcfiterLauerSimpleCycles<V,​E>
extends java.lang.Object
implements DirectedSimpleCycles<V,​E>
    Find all simple cycles of a directed graph using the Schwarcfiter and Lauer's algorithm.

    See:
    J.L.Szwarcfiter and P.E.Lauer, Finding the elementary cycles of a directed graph in O(n + m) per cycle, Technical Report Series, #60, May 1974, Univ. of Newcastle upon Tyne, Newcastle upon Tyne, England.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private java.util.Map<V,​java.util.Set<V>> bSets  
      private java.util.List<java.util.List<V>> cycles  
      private DirectedGraph<V,​E> graph  
      private V[] iToV  
      private java.util.Set<V> marked  
      private int[] position  
      private boolean[] reach  
      private java.util.Map<V,​java.util.Set<V>> removed  
      private java.util.ArrayDeque<V> stack  
      private java.util.List<V> startVertices  
      private java.util.Map<V,​java.lang.Integer> vToI  

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      private void clearState()  
      private boolean cycle​(int v, int q)  
      java.util.List<java.util.List<V>> findSimpleCycles()
      Finds the simple cycles of the graph.
      Note that the full algorithm is executed on every call since the graph may have changed between calls.
      private java.util.Set<V> getBSet​(V v)  
      DirectedGraph<V,​E> getGraph()
      Returns the graph on which the simple cycle search algorithm is executed by this object.
      private java.util.Set<V> getRemoved​(V v)  
      private void initState()  
      private void noCycle​(int x, int y)  
      void setGraph​(DirectedGraph<V,​E> graph)
      Sets the graph on which the simple cycle search algorithm is executed by this object.
      private java.lang.Integer toI​(V v)  
      private V toV​(int i)  
      private void unmark​(int x)  

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • cycles

        private java.util.List<java.util.List<V>> cycles

      • iToV

        private V[] iToV

      • vToI

        private java.util.Map<V,​java.lang.Integer> vToI

      • bSets

        private java.util.Map<V,​java.util.Set<V>> bSets

      • stack

        private java.util.ArrayDeque<V> stack

      • marked

        private java.util.Set<V> marked

      • removed

        private java.util.Map<V,​java.util.Set<V>> removed

      • position

        private int[] position

      • reach

        private boolean[] reach

      • startVertices

        private java.util.List<V> startVertices

    • Constructor Detail

      • SzwarcfiterLauerSimpleCycles

        public SzwarcfiterLauerSimpleCycles()
        Create a simple cycle finder with an unspecified graph.

      • SzwarcfiterLauerSimpleCycles

        public SzwarcfiterLauerSimpleCycles​(DirectedGraph<V,​E> graph)
        Create a simple cycle finder for the specified graph.
        Parameters:
        graph - - the DirectedGraph in which to find cycles.
        Throws:
        java.lang.IllegalArgumentException - if the graph argument is null.

    • Method Detail

      • getGraph

        public DirectedGraph<V,​E> getGraph()
        Returns the graph on which the simple cycle search algorithm is executed by this object.
        Specified by:
        getGraph in interface DirectedSimpleCycles<V,​E>
        Returns:
        The graph.

      • setGraph

        public void setGraph​(DirectedGraph<V,​E> graph)
        Sets the graph on which the simple cycle search algorithm is executed by this object.
        Specified by:
        setGraph in interface DirectedSimpleCycles<V,​E>
        Parameters:
        graph - the graph.

      • findSimpleCycles

        public java.util.List<java.util.List<V>> findSimpleCycles()
        Finds the simple cycles of the graph.
        Note that the full algorithm is executed on every call since the graph may have changed between calls.
        Specified by:
        findSimpleCycles in interface DirectedSimpleCycles<V,​E>
        Returns:
        The list of all simple cycles. Possibly empty but never null.

      • cycle

        private boolean cycle​(int v,
                      int q)

      • noCycle

        private void noCycle​(int x,
                     int y)

      • unmark

        private void unmark​(int x)

      • initState

        private void initState()

      • clearState

        private void clearState()

      • toI

        private java.lang.Integer toI​(V v)

      • toV

        private V toV​(int i)

      • getBSet

        private java.util.Set<V> getBSet​(V v)

      • getRemoved

        private java.util.Set<V> getRemoved​(V v)