public Colour ChooseColor(IColouredGraph g, Vertex v)
{
//some FP here //breaking away from C-style syntax
IEnumerable<Vertex> neighbours = g.GetNeighbors(g,v);
var validColours = _colours.Where(c => !neighbours.Any(n => _nodes.Where(_n => _n.Vertex.ID == n.ID).Any(node => (node.Vertex.Colour != null && node.Vertex.Colour.GetColour().Equals(c.GetColour()))))).Select(c => c);
if (validColours.Any())
return validColours.First();
else
{
// should not come here. Just a fail safe precaution.
_colours.Add(new Colour(colour + (VerticesCount + 1).ToString()));
return _colours.Last();
}
}
private bool IsVertexPresentInNeighbours(List<Vertex> neighbours, Vertex v)
{
bool isPresent = false;
foreach (var vertex in neighbours)
{
if (vertex.ID == v.ID)
{
isPresent = true;
break;
}
}
return isPresent;
}
//Keeping the signature same for the heck of it.
//Otherwise I wouldnt be needing the graph datatype to be passed in here.
//May be in a pure functional programming this might make sense.
public IColouredGraph AddEdge(IColouredGraph g, Vertex startingVertex, Vertex endingVertex)
{
AddVerticesAndItsNeighbours(startingVertex, endingVertex);
_edges.Add(new Edge(startingVertex, endingVertex));
return this;
}
private int GetDegreeOfVertex(Vertex v)
{
int degree = 0;
foreach (var node in _nodes)
{
if (node.Vertex.ID == v.ID)
{
degree = node.DegreeOfVertex;
break;
}
}
return degree;
}
private void AddVerticesAndItsNeighbours(Vertex startingVertex, Vertex endingVertex)
{
int graphNodeCount = 0;
bool startingVertexAlreadyAdded = false, endingVertexAlreadyAdded = false;
//doing good old c-way
for (graphNodeCount = 0; graphNodeCount < _nodes.Count; graphNodeCount++)
{
if (_nodes[graphNodeCount].Vertex.ID == startingVertex.ID)
{
//implicitly - has atleast one neighbour
if (!IsVertexPresentInNeighbours(_nodes[graphNodeCount].AdjacentVertices, endingVertex))
{
_nodes[graphNodeCount].AdjacentVertices.Add(endingVertex);
_nodes[graphNodeCount].DegreeOfVertex++;
}
startingVertexAlreadyAdded = true;
}
if (_nodes[graphNodeCount].Vertex.ID == endingVertex.ID)
{
//implicitly - has atleast one neighbour
if (!IsVertexPresentInNeighbours(_nodes[graphNodeCount].AdjacentVertices, startingVertex))
{
_nodes[graphNodeCount].AdjacentVertices.Add(startingVertex);
_nodes[graphNodeCount].DegreeOfVertex++;
}
endingVertexAlreadyAdded = true;
}
}
//C# style of iteration
//foreach (var graphNode in _nodes)
//{
// if (graphNode.Vertex.ID == startingVertex.ID)
// {
// if (!IsVertexPresentInNeighbours(graphNode.AdjacentVertices, endingVertex))
// {
// graphNode.AdjacentVertices.Add(new Vertex(endingVertex.ID));
// graphNode.DegreeOfVertex++;
// }
// startingVertexAlreadyAdded = true;
// }
// if (graphNode.Vertex.ID == endingVertex.ID)
// {
// //implicitly - has atleast one neighbour
// if (!IsVertexPresentInNeighbours(graphNode.AdjacentVertices, startingVertex))
// {
// graphNode.AdjacentVertices.Add(new Vertex(startingVertex.ID));
// graphNode.DegreeOfVertex++;
// }
// endingVertexAlreadyAdded = true;
// }
//}
if (!startingVertexAlreadyAdded)
_nodes.Add(new GraphNode(startingVertex, 1, new List<Vertex>() { new Vertex(endingVertex.ID) }));
if (!endingVertexAlreadyAdded)
_nodes.Add(new GraphNode(endingVertex, 1, new List<Vertex>() { new Vertex(startingVertex.ID) }));
if (_nodes.Count > VerticesCount)
throw new Exception("Number of vertices exceeded the intial contract as stated in the file.");
}
public IEnumerable<Vertex> GetNeighbors(IColouredGraph g, Vertex v)
{
int graphNodeCount = 0;
IEnumerable<Vertex> neighbours = null;
for (graphNodeCount = 0; graphNodeCount < _nodes.Count; graphNodeCount++)
{
if (_nodes[graphNodeCount].Vertex.ID == v.ID)
{
neighbours = _nodes[graphNodeCount].AdjacentVertices;
}
}
if (neighbours == null)
neighbours = new List<Vertex>();
return neighbours;
}
public Edge(Vertex startingVertex, Vertex endingVertex)
{
StartingVertex = startingVertex;
EndingVertex = endingVertex;
}
public GraphNode(Vertex vertex, int degree, List<Vertex> adjacentVertices)
{
Vertex = vertex;
DegreeOfVertex = degree;
AdjacentVertices = adjacentVertices;
}