Package com.jgalgo

Interface EulerianTourAlgo


  • public interface EulerianTourAlgo
    Eulerian tour calculation algorithm.

    An Eulerian tour is a tour that visits every edge exactly once (allowing for revisiting vertices). For a connected undirected graph, if all vertices have an even degree, an Eulerian cycle will be found. If exactly two vertices have an odd degree, called \(s,t\), an Eulerian tour that start at \(s\) and ends at \(t\) exists. For any other vertices degrees an Eulerian tour does not exists. For a strongly connected directed graph, the in-degree and out-degree of each vertex must be equal for an Eulerian cycle to exists. If exactly one vertex \(s\) has one more out-edge than in-edges, and one vertex \(t\) has one more in-edge than out-edges, an Eulerian tour that start at \(s\) and ends at \(t\) exists.

    Author:
    Barak Ugav
    See Also:
    Wikipedia, TSPMetricMSTAppx, TSPMetricMatchingAppx
    • Method Detail

      • computeEulerianTour

        Path computeEulerianTour​(Graph g)
        Compute an Eulerian tour in the graph that visit all edges exactly once.

        The graph is assumed to be (strongly) connected. Either a cycle or tour will be found, depending on the vertices degrees.

        Parameters:
        g - a graph
        Returns:
        an Eulerian tour that visit all edges of the graph exactly once
        Throws:
        IllegalArgumentException - if there is no Eulerian tour in the graph