private GraphNode <T> GetNodeWithUnusedEdges(IEnumerable <GraphNode <T> > path) { foreach (var node in path) { if (!_directedGraph.Neighbors.ContainsKey(node)) { continue; } foreach (var neighbor in _directedGraph.Neighbors[node]) { foreach (var edge in _directedGraph.GetEdges(node, neighbor)) { if (edge.Color == Color.Uncolored) { return(node); } } } } return(null); }
//for directed Graph public static IReadOnlyDictionary <GraphNode <T>, GraphNode <T> > RunDijkstraFrom(DirectedGraph <T> graph, T src) { if (!graph.Nodes.TryGetValue(new GraphNode <T>(src), out var source)) { return(null); } var predecessors = new Dictionary <GraphNode <T>, GraphNode <T> >();//keeps track of the shortest path predecessor //using Dijkstra's algorithm var priorityQ = new MinHeap <GraphNode <T> >(new GraphNode <T>(default(T))); foreach (var node in graph.Nodes) { node.Weight = source.Equals(node) ? 0 : int.MaxValue; priorityQ.Add(node); predecessors[source] = null; } while (priorityQ.Count != 0) { var minNode = priorityQ.GetMin(); if (!graph.Neighbors.ContainsKey(minNode)) { priorityQ.ExtractMin(); continue; } foreach (var neighbor in graph.Neighbors[minNode]) { graph.Nodes.TryGetValue(neighbor, out var neighborNode); var edges = graph.GetEdges(minNode, neighbor); foreach (var edge in edges) { if (neighborNode.Weight > minNode.Weight + edge.Weight) { neighborNode.Weight = minNode.Weight + edge.Weight; predecessors[neighborNode] = minNode; } } } priorityQ.ExtractMin(); } return(predecessors); }