public void Init()
{
this.parents = new Dictionary <string, string>();
this.distances = new Dictionary <string, int>();
this.currentDistance = 0;
this.currentVertex = null;
this.algo = null;
}
private void Search(IUndirectedGraph <string, Edge <string> > graph, string rootVertex)
{
Console.WriteLine(rootVertex);
algo = new UndirectedBreadthFirstSearchAlgorithm <string, Edge <string> >(graph);
try
{
algo.InitializeVertex += new VertexEventHandler <string>(this.InitializeVertex);
algo.DiscoverVertex += new VertexEventHandler <string>(this.DiscoverVertex);
algo.ExamineVertex += new VertexEventHandler <string>(this.ExamineVertex);
algo.TreeEdge += new EdgeEventHandler <string, Edge <string> >(this.TreeEdge);
algo.NonTreeEdge += new EdgeEventHandler <string, Edge <string> >(this.NonTreeEdge);
algo.GrayTarget += new EdgeEventHandler <string, Edge <string> >(this.GrayTarget);
algo.BlackTarget += new EdgeEventHandler <string, Edge <string> >(this.BlackTarget);
algo.FinishVertex += new VertexEventHandler <string>(this.FinishVertex);
parents.Clear();
distances.Clear();
currentDistance = 0;
sourceVertex = rootVertex;
foreach (string v in this.algo.VisitedGraph.Vertices)
{
distances[v] = int.MaxValue;
parents[v] = v;
}
distances[sourceVertex] = 0;
algo.Compute(sourceVertex);
CheckBfs();
}
finally
{
algo.InitializeVertex -= new VertexEventHandler <string>(this.InitializeVertex);
algo.DiscoverVertex -= new VertexEventHandler <string>(this.DiscoverVertex);
algo.ExamineVertex -= new VertexEventHandler <string>(this.ExamineVertex);
algo.TreeEdge -= new EdgeEventHandler <string, Edge <string> >(this.TreeEdge);
algo.NonTreeEdge -= new EdgeEventHandler <string, Edge <string> >(this.NonTreeEdge);
algo.GrayTarget -= new EdgeEventHandler <string, Edge <string> >(this.GrayTarget);
algo.BlackTarget -= new EdgeEventHandler <string, Edge <string> >(this.BlackTarget);
algo.FinishVertex -= new VertexEventHandler <string>(this.FinishVertex);
}
}
public void RunBfs <TVertex, TEdge>(IUndirectedGraph <TVertex, TEdge> g, TVertex sourceVertex)
where TEdge : IEdge <TVertex>
{
var parents = new Dictionary <TVertex, TVertex>();
var distances = new Dictionary <TVertex, int>();
TVertex currentVertex = default(TVertex);
int currentDistance = 0;
var algo = new UndirectedBreadthFirstSearchAlgorithm <TVertex, TEdge>(g);
algo.InitializeVertex += u =>
{
Assert.AreEqual(algo.VertexColors[u], GraphColor.White);
};
algo.DiscoverVertex += u =>
{
Assert.AreEqual(algo.VertexColors[u], GraphColor.Gray);
if (u.Equals(sourceVertex))
{
currentVertex = sourceVertex;
}
else
{
Assert.IsNotNull(currentVertex);
Assert.AreEqual(parents[u], currentVertex);
Assert.AreEqual(distances[u], currentDistance + 1);
Assert.AreEqual(distances[u], distances[parents[u]] + 1);
}
};
algo.ExamineEdge += args =>
{
Assert.IsTrue(args.Source.Equals(currentVertex) ||
args.Target.Equals(currentVertex));
};
algo.ExamineVertex += args =>
{
var u = args;
currentVertex = u;
// Ensure that the distances monotonically increase.
Assert.IsTrue(
distances[u] == currentDistance ||
distances[u] == currentDistance + 1
);
if (distances[u] == currentDistance + 1) // new level
{
++currentDistance;
}
};
algo.TreeEdge += (sender, args) =>
{
var u = args.Edge.Source;
var v = args.Edge.Target;
if (algo.VertexColors[v] == GraphColor.Gray)
{
var temp = u;
u = v;
v = temp;
}
Assert.AreEqual(algo.VertexColors[v], GraphColor.White);
Assert.AreEqual(distances[u], currentDistance);
parents[v] = u;
distances[v] = distances[u] + 1;
};
algo.NonTreeEdge += (sender, args) =>
{
var u = args.Edge.Source;
var v = args.Edge.Target;
if (algo.VertexColors[v] != GraphColor.White)
{
var temp = u;
u = v;
v = temp;
}
Assert.IsFalse(algo.VertexColors[v] == GraphColor.White);
if (algo.VisitedGraph.IsDirected)
{
// cross or back edge
Assert.IsTrue(distances[v] <= distances[u] + 1);
}
else
{
// cross edge (or going backwards on a tree edge)
Assert.IsTrue(
distances[v] == distances[u] ||
distances[v] == distances[u] + 1 ||
distances[v] == distances[u] - 1
);
}
};
algo.GrayTarget += (sender, args) =>
{
//Assert.AreEqual(algo.VertexColors[args.Edge.Target], GraphColor.Gray);
};
algo.BlackTarget += (sender, args) =>
{
//Assert.AreEqual(algo.VertexColors[args.Edge.Target], GraphColor.Black);
//foreach (var e in algo.VisitedGraph.AdjacentEdges(args.Edge.Target))
// Assert.IsFalse(algo.VertexColors[e.Target] == GraphColor.White);
};
algo.FinishVertex += args =>
{
Assert.AreEqual(algo.VertexColors[args], GraphColor.Black);
};
parents.Clear();
distances.Clear();
currentDistance = 0;
foreach (var v in g.Vertices)
{
distances[v] = int.MaxValue;
parents[v] = v;
}
distances[sourceVertex] = 0;
algo.Compute(sourceVertex);
// All white vertices should be unreachable from the source.
foreach (var v in g.Vertices)
{
if (algo.VertexColors[v] == GraphColor.White)
{
//!IsReachable(start,u,g);
}
}
// The shortest path to a child should be one longer than
// shortest path to the parent.
foreach (var v in g.Vertices)
{
if (!parents[v].Equals(v)) // *ui not the root of the bfs tree
{
Assert.AreEqual(distances[v], distances[parents[v]] + 1);
}
}
}
