public void UndirectedGraph32_Explore_Test()
{
var g = GraphFactory.CreateUndirectedGraph32();
var stats = new DfsStats(g.V);
Dfs.Explore(g, 0, stats); //explore Vertice A
Debug.WriteLine(stats.ToString());
}
public static DfsStats DepthFirstSearch(GraphBase g)
{
var ds = new DfsStats(g.V);
for (var i = 0; i < g.V; i++)
ds.Visited[i] = false;
for (var i = 0; i < g.V; i++)
if (!ds.Visited[i])
{
ds.ComponentCount++;
Explore(g, i, ds);
}
return ds;
}
public static DfsStats StrongConnectedComponentAlgorithm(DirectedGraph g)
{
g.ReverseGraph();//reverse G
var linearization = GetLinearization(g);
var ds = new DfsStats(g.V) { Clock = 1, ComponentCount = 0 };
g.ReverseGraph();//reverse G back
foreach (var v in linearization)
{
if (!ds.Visited[v])
{
ds.ComponentCount++;
Explore(g, v, ds);
}
}
return ds;
}
public static void Explore(GraphBase g, int v, DfsStats dfsStats)
{
PreVisitVertice(v, dfsStats);
foreach (var e in g.Adjacent(v))
{
if (!dfsStats.Visited[e.V2])
{
Explore(g, e.V2, dfsStats);
}
//else if (e < v)
//only directed graph has 'back edge'
else if (g is DirectedGraph && e.V2 < v)//e < v is not right
{
dfsStats.BackEdges.Add(new Edge { V1 = v, V2 = e.V2 });
}
}
PostVisitVertice(v, dfsStats);
}
private static void PreVisitVertice(int v, DfsStats dfsStats)
{
dfsStats.Visited[v] = true;
dfsStats.ComponentNum[v] = dfsStats.ComponentCount;
dfsStats.PreVisit[v] = dfsStats.Clock++;
}
private static void PostVisitVertice(int v, DfsStats dfsStats)
{
dfsStats.PostVisit[v] = dfsStats.Clock++;
dfsStats.Linearization.AddFirst(v);
}
