public List <Path> Dijkstra(IVertex source)
{
var paths = new Dictionary <IVertex, PathBuilder>();
var flags = new Dictionary <IVertex, bool>();
var vertices = new List <IVertex>(Vertices);
foreach (var v in vertices)
{
paths[v] = new PathBuilder(v, null, v == source ? 0 : int.MaxValue);
flags[v] = false;
}
var unreachable = new Vertex(-1);
while (true)
{
var least = new PathBuilder(unreachable, null, int.MaxValue);
foreach (var v in vertices)
{
if (!flags[v] && paths[v].Weight < least.Weight)
{
least = paths[v];
}
}
if (least.Source == unreachable)
{
break;
}
var src = least.Source;
flags[src] = true;
foreach (var dst in src.Neighbors.Select(Vertex))
{
var weight = EdgeWeight(src, dst);
if (weight <= 0 || flags[dst])
{
continue;
}
var oldPath = paths[dst];
var newWeight = weight + least.Weight;
if (newWeight < oldPath.Weight)
{
paths[oldPath.Source] = new PathBuilder(oldPath.Source, least, newWeight);
}
}
}
var pathsFound = new List <PathBuilder>(paths.Values);
var result = pathsFound.Select(p => p.Build(this).Reverse()).OrderBy(p => p.First.Id).ToList();
return(result);
}
public PathBuilder Reverse()
{
var currentNode = new PathBuilder(Source, null, 0);
var currentWeight = Weight;
var iterator = Next;
while (iterator != null)
{
currentNode = new PathBuilder(iterator.Source, currentNode, currentWeight - iterator.Weight);
iterator = iterator.Next;
}
return(currentNode);
}
public PathBuilder(IVertex source, PathBuilder next, int weight)
{
Source = source;
Next = next;
Weight = weight;
}