Class GreedyVCImpl<V,​E>

  • Type Parameters:
    V - the graph vertex type
    E - the graph edge type
    All Implemented Interfaces:

    public class GreedyVCImpl<V,​E>
    extends java.lang.Object
    implements VertexCoverAlgorithm<V>
    Greedy algorithm to find a vertex cover for a graph. A vertex cover is a set of vertices that touches all the edges in the graph. The graph's vertex set is a trivial cover. However, a minimal vertex set (or at least an approximation for it) is usually desired. Finding a true minimal vertex cover is an NP-Complete problem. For more on the vertex cover problem, see Note: this class supports pseudo-graphs Runtime: $O(|E| \log |V|)$ This class produces often, but not always, better solutions than the 2-approximation algorithms. Nevertheless, there are instances where the solution is significantly worse. In those cases, consider using ClarksonTwoApproxVCImpl.
    Joris Kinable
    • Constructor Detail

      • GreedyVCImpl

        public GreedyVCImpl​(Graph<V,​E> graph)
        Constructs a new GreedyVCImpl instance where all vertices have uniform weights.
        graph - input graph
      • GreedyVCImpl

        public GreedyVCImpl​(Graph<V,​E> graph,
                            java.util.Map<V,​java.lang.Double> vertexWeightMap)
        Constructs a new GreedyVCImpl instance
        graph - input graph
        vertexWeightMap - mapping of vertex weights
    • Method Detail

      • getVertexCover

        public VertexCoverAlgorithm.VertexCover<V> getVertexCover()
        Finds a greedy solution to the minimum weighted vertex cover problem. At each iteration, the algorithm picks the vertex v with the smallest ratio weight(v)/degree(v) and adds it to the cover. Next vertex v and all edges incident to it are removed. The process repeats until all vertices are covered. Runtime: O(|E|*log|V|)
        Specified by:
        getVertexCover in interface VertexCoverAlgorithm<V>
        greedy solution