public Dijkstra(Graph <T> graph, T source)
{
_graph = graph;
_source = graph.Get(source);
if (_source == null)
{
throw new ArgumentException(string.Format("Vertex {0} not found", source));
}
}
public void Run()
{
// setup:
_source.Score = 0;
var unexplored = GetAllNodes();
var edges = GetSortedEdges();
var explored = new List <Vertex <T> > {
_source
};
unexplored.Remove(_source);
// main loop:
while (unexplored.Any() && edges.Any())
{
var least = edges.Min();
edges.Remove(least);
if (!_graph.IsDirected)
{
edges.Remove(new Edge <T>(least.To, least.From, least.Weight));
}
if (explored.Contains(least.From) && !explored.Contains(least.To))
{
least.To.Score = least.From.Score + least.Weight;
foreach (var edge in least.To.Edges)
{
var v = _graph.Get(edge.Key);
int edgeWeight = edge.Value;
if (v.Score > least.To.Score + edgeWeight)
{
v.Score = least.To.Score + edgeWeight;
}
}
unexplored.Remove(least.To);
explored.Add(least.To);
}
}
}
public void TestSmallGraph()
{
var g = new Graph<int>();
for (int i = 0; i < 4; ++i) g.GetOrCreateVertex(i);
g.Get(0).AddEdge(1, 1);
g.Get(0).AddEdge(2, 3);
g.Get(1).AddEdge(2, 1);
g.Get(1).AddEdge(3, 3);
g.Get(2).AddEdge(3, 1);
var algorithm = new Dijkstra<int>(g, 0);
algorithm.Run();
Assert.AreEqual(0, g.Get(0).Score);
Assert.AreEqual(1, g.Get(1).Score);
Assert.AreEqual(2, g.Get(2).Score);
Assert.AreEqual(3, g.Get(3).Score);
}
public void TestSmallGraph()
{
var g = new Graph <int>();
for (int i = 0; i < 4; ++i)
{
g.GetOrCreateVertex(i);
}
g.Get(0).AddEdge(1, 1);
g.Get(0).AddEdge(2, 3);
g.Get(1).AddEdge(2, 1);
g.Get(1).AddEdge(3, 3);
g.Get(2).AddEdge(3, 1);
var algorithm = new Dijkstra <int>(g, 0);
algorithm.Run();
Assert.AreEqual(0, g.Get(0).Score);
Assert.AreEqual(1, g.Get(1).Score);
Assert.AreEqual(2, g.Get(2).Score);
Assert.AreEqual(3, g.Get(3).Score);
}
public Vertex <T> Get(T key)
{
return(_g.Get(key));
}
