private static Graph ReadFromFile(string fileName)
{
//The format of line is:
// Id: id_neighbour_1, id_neighbour_2, ... , id_nieghbour_n
var g = new Graph();
var allLines = File.ReadAllLines(fileName);
var splittedAllLines = allLines.Select(x => x.Split(':'));
if (splittedAllLines.Any(x => x.Count() != 2))
throw new InvalidFileFormatException();
foreach (var id in splittedAllLines.Select(x => x[0]))
{
g.AddVertex(ParseVertexId(id));
}
foreach (var line in splittedAllLines)
{
var fromId = ParseVertexId(line[0]);
var neighbours = line[1].Split(',');
foreach (var neighbour in neighbours)
{
int toId = ParseVertexId(neighbour);
if(!g.ContainsVertex(toId))
throw new InvalidFileFormatException();
g.AddDirectedEdge(fromId, toId);
}
}
return g;
}
public BipartiteTestingAlgorithm(Graph graph)
{
this.verticies = graph.AllVerticies.ToList();
vertexColors = new Dictionary<int, Color?>();
foreach (var vertex in graph.AllVerticies)
{
vertexColors[vertex.Id] = null;
}
}
private Edge? GetEdgeToExtend(Graph g, Edge e)
{
foreach (var e2 in NonplanarSubgraph.GetAllEdges())
{
if (!g.ContainsEdge(e2.U, e2.V) && g.ContainsEdge(e.V, e2.U) && g.ContainsEdge(e.V, e2.V))
{
return e2;
}
}
return null;
}
private void ExtendNonplanarSubgraph(Graph g, Edge e)
{
var toExtend = GetEdgeToExtend(g, e);
if (toExtend != null)
{
NonplanarSubgraph.RemoveEdge(toExtend.Value);
NonplanarSubgraph.AddVertex(e.V);
NonplanarSubgraph.AddUndirectedEdge(e.V, toExtend.Value.V);
NonplanarSubgraph.AddUndirectedEdge(e.V, toExtend.Value.U);
}
}
public static Graph CreateBipartiteGraph(int n, int m)
{
var graph = new Graph();
graph.AddVerticiesRange(n + m);
for (int i = 0; i < n; i++)
{
for (int j = n; j < n+m; j++)
{
graph.AddUndirectedEdge(i, j);
}
}
return graph;
}
public static Graph CreateCompleteGraph(int size)
{
var graph = new Graph();
graph.AddVerticiesRange(size);
for (int i = 0; i < size; i++)
{
for (int j = 0; j < i; j++)
{
graph.AddUndirectedEdge(i, j);
}
}
return graph;
}
private bool IsPlanar(Graph g)
{
Counter++;
if (g.IsCompleteBipartite(3, 3) || g.IsComplete(5))
{
NonplanarSubgraph = g;
return false;
}
if (g.Size == 5)
return true;
foreach (var edge in g.GetAllEdges())
{
var h = g.Shrink(edge.U, edge.V);
var isPlanar = IsPlanar(h);
if (!isPlanar)
{
ExtendNonplanarSubgraph(g, edge);
return false;
}
}
return true;
}
public PlanarityTestingAlgorithm(Graph inputGraph)
{
this.inputGraph = inputGraph;
}
public Graph Shrink(int n, int m)
{
var h = new Graph();
foreach (var v in AllVerticies.Where(x => x.Id != m))
{
h.AddVertex(v.Id);
}
foreach (var vertex in AllVerticies.Where(x => x.Id != m))
{
foreach (var neighbour in vertex.AllNeighbours.Where(x => x.Id != m))
{
h.AddDirectedEdge(vertex.Id, neighbour.Id);
}
}
var mVertex = verticies[m];
foreach (var neighbourOfM in mVertex.AllNeighbours.Where(x => x.Id != n))
{
h.AddUndirectedEdge(n, neighbourOfM.Id);
}
return h;
}
