GreedyVCImpl (JGraphT : a free Java graph library)

java.lang.Object
- org.jgrapht.alg.vertexcover.GreedyVCImpl<V,E>

Type Parameters:

V - the graph vertex type

E - the graph edge type

All Implemented Interfaces:

VertexCoverAlgorithm<V>
```
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 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.

Author:

Joris Kinable

Nested Class Summary
- Nested classes/interfaces inherited from interface org.jgrapht.alg.interfaces.VertexCoverAlgorithm
  VertexCoverAlgorithm.VertexCover<V>, VertexCoverAlgorithm.VertexCoverImpl<V>

Constructor Summary

Constructors
Constructor	Description
`GreedyVCImpl(Graph<V,E> graph)`	Constructs a new GreedyVCImpl instance where all vertices have uniform weights.
`GreedyVCImpl(Graph<V,E> graph, java.util.Map<V,java.lang.Double> vertexWeightMap)`	Constructs a new GreedyVCImpl instance

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`VertexCoverAlgorithm.VertexCover<V>`	`getVertexCover()`	Finds a greedy solution to the minimum weighted vertex cover problem.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - GreedyVCImpl
```
public GreedyVCImpl(Graph<V,E> graph)
```
    Constructs a new GreedyVCImpl instance where all vertices have uniform weights.
    
    Parameters:
    
    graph - input graph
  - GreedyVCImpl
```
public GreedyVCImpl(Graph<V,E> graph,
                    java.util.Map<V,java.lang.Double> vertexWeightMap)
```
    Constructs a new GreedyVCImpl instance
    
    Parameters:
    
    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>
    
    Returns:
    
    greedy solution