org.jgrapht.alg.vertexcover

Class GreedyVCImpl<V,E>

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

public class GreedyVCImpl<V,E>
extends Object
implements MinimumWeightedVertexCoverAlgorithm<V,E>
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 http://mathworld.wolfram.com/VertexCover.html 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.
Since:
Nov 6, 2003
Author:
Joris Kinable
• Constructor Detail

• GreedyVCImpl

public GreedyVCImpl()
• Method Detail

• getVertexCover

public MinimumVertexCoverAlgorithm.VertexCover<V> getVertexCover(UndirectedGraph<V,E> graph,
Map<V,Double> vertexWeightMap)
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 MinimumWeightedVertexCoverAlgorithm<V,E>
Parameters:
graph - input graph
vertexWeightMap - mapping of vertex weights
Returns:
greedy solution