public static DijkstraValues GetDijkstraValues(this IGraphNode node, bool ignoreDirection = false, GraphSearchMode searchMode = GraphSearchMode.ShortestPath)
{
if (searchMode != GraphSearchMode.ShortestPath)
{
throw new NotImplementedException();
}
var allGraphNodes =
node.Entity.Level.Entities.Where(entity => entity.Implements <IGraphNode>())
.Select(entity => entity.GetImplementation <IGraphNode>()).ToList();
var distances = new Dictionary <IGraphNode, float>();
var predecessors = new Dictionary <IGraphNode, IGraphNode>();
foreach (var graphNode in allGraphNodes)
{
distances.Add(graphNode, float.MaxValue);
predecessors.Add(graphNode, null);
}
distances[node] = 0;
while (allGraphNodes.Count > 0)
{
var currentNode = allGraphNodes.OrderBy(_ => distances[_]).First();
allGraphNodes.Remove(currentNode);
foreach (var neighborTuple in GetNeighbors(currentNode, ignoreDirection))
{
if (!allGraphNodes.Contains(neighborTuple.Item1))
{
continue;
}
var neighborDistance = distances[neighborTuple.Item1];
var alternativeDistance = distances[currentNode] + neighborTuple.Item2;
if (alternativeDistance < neighborDistance)
{
distances[neighborTuple.Item1] = alternativeDistance;
predecessors[neighborTuple.Item1] = currentNode;
}
}
}
return(new DijkstraValues(distances, predecessors));
}
public static bool FindPath(Vertex fromNode, Vertex target, List <Vertex> path, GraphSearchMode searchMode = GraphSearchMode.DepthFirst)
{
Queue <Vertex> queue = new Queue <Vertex>();
if (fromNode == null || fromNode.Visited)
{
return(false);
}
if (searchMode == GraphSearchMode.DepthFirst)
{
path.Add(fromNode);
fromNode.Visited = true;
if (fromNode.Value.CompareTo(target.Value) == 0)
{
return(true);
}
if (fromNode.ConnectToNodes != null)
{
foreach (var destination in fromNode.ConnectToNodes)
{
var found = FindPath(destination, target, path, searchMode);
if (found)
{
return(true);
}
}
}
}
else
{
fromNode.Visited = true;
queue.Enqueue(fromNode);
while (queue.Count > 0)
{
var v = queue.Dequeue();
path.Add(v);
if (v.Value.CompareTo(target.Value) == 0)
{
return(true);
}
if (v.ConnectToNodes != null)
{
foreach (Vertex adjacent in v.ConnectToNodes)
{
if (!adjacent.Visited)
{
adjacent.Visited = true;
queue.Enqueue(adjacent);
}
}
}
}
}
return(false);
}
