/// <summary>
/// Computes the connected components.
/// </summary>
/// <param name="g">graph to explore</param>
/// <param name="components">component map where results are recorded</param>
/// <returns>number of components</returns>
public static int ConnectedComponents(
IVertexListGraph g,
VertexIntDictionary components)
{
ConnectedComponentsAlgorithm conn =
new ConnectedComponentsAlgorithm(g, components);
return(conn.Compute());
}
/// <summary>
/// Computes the connected components of a graph
/// </summary>
/// <typeparam name="TVertex">type of the vertices</typeparam>
/// <typeparam name="TEdge">type of the edges</typeparam>
/// <param name="g"></param>
/// <param name="components"></param>
/// <returns>number of components</returns>
public static int ConnectedComponents <TVertex, TEdge>
(this IUndirectedGraph <TVertex, TEdge> g, IDictionary <TVertex, int> components)
where TEdge : IEdge <TVertex>
{
Contract.Requires(g != null);
Contract.Requires(components != null);
var conn = new ConnectedComponentsAlgorithm <TVertex, TEdge>(g, components);
conn.Compute();
return(conn.ComponentCount);
}
public static int ConnectedComponents <TVertex, TEdge>(
IUndirectedGraph <TVertex, TEdge> g,
TVertex startVertex,
IDictionary <TVertex, int> components)
where TEdge : IEdge <TVertex>
{
GraphContracts.AssumeNotNull(g, "g");
GraphContracts.Assume(g.ContainsVertex(startVertex), "g.ContainsVertex(startVertex)");
GraphContracts.AssumeNotNull(components, "components");
var conn = new ConnectedComponentsAlgorithm <TVertex, TEdge>(g, components);
conn.Compute(startVertex);
return(conn.ComponentCount);
}
public bool isEulerian()
{
var componentsAlgo = new ConnectedComponentsAlgorithm <TVertex, UndirectedEdge <TVertex> >(this.graph);
componentsAlgo.Compute();
// Only one component could contain edges
bool[] hasEdgesInComponent = new bool[componentsAlgo.ComponentCount];
foreach (var verticeAndComponent in componentsAlgo.Components)
{
hasEdgesInComponent[verticeAndComponent.Value] = graph.AdjacentEdges(verticeAndComponent.Key).Count() > 0;
}
var t = firstAndSecondIndexOfTrue(hasEdgesInComponent);
int?firstIndex = t.Item1, secondIndex = t.Item2;
// No edges at all or More than one component contain edges
if (!firstIndex.HasValue || secondIndex.HasValue)
{
return(false);
}
else
{
// Now only one component contains edges, check is it an eulerian component
// If component contain one vertex it is an eulerian component
if (componentsAlgo.Components.First(x => x.Value == firstIndex.Value).Key
.Equals(componentsAlgo.Components.Last(x => x.Value == firstIndex.Value).Key))
{
return(true);
}
foreach (var verticeAndComponent in componentsAlgo.Components)
{
// Vertice in selected component and has even count of edges
if (verticeAndComponent.Value == firstIndex.Value &&
graph.AdjacentEdges(verticeAndComponent.Key).Count() % 2 == 1)
{
return(false);
}
}
return(true);
}
}
public ComponentWithEdges checkComponentsWithEdges()
{
var componentsAlgo = new ConnectedComponentsAlgorithm <TVertex, UndirectedEdge <TVertex> >(this.graph);
componentsAlgo.Compute();
bool[] hasEdgesInComponent = new bool[componentsAlgo.ComponentCount];
foreach (var verticeAndComponent in componentsAlgo.Components)
{
hasEdgesInComponent[verticeAndComponent.Value] = !graph.IsAdjacentEdgesEmpty(verticeAndComponent.Key);
}
var t = firstAndSecondIndexOfTrue(hasEdgesInComponent);
int?firstIndex = t.Item1, secondIndex = t.Item2;
if (!firstIndex.HasValue)
{
return(ComponentWithEdges.NoComponent);
}
if (secondIndex.HasValue)
{
return(ComponentWithEdges.ManyComponents);
}
return(ComponentWithEdges.OneComponent);
}
/// <summary>
/// Computes the connected components.
/// </summary>
/// <param name="g">graph to explore</param>
/// <param name="components">component map where results are recorded</param>
/// <returns>number of components</returns>
public static int ConnectedComponents(
IVertexListGraph g,
VertexIntDictionary components)
{
ConnectedComponentsAlgorithm conn =
new ConnectedComponentsAlgorithm(g,components);
return conn.Compute();
}
