private void InitializeGraph(Graph graph, string startingNode)
{
foreach (Node node in graph.Nodes.Values)
{
node.DistanceFromStart = double.PositiveInfinity;
}
graph.Nodes[startingNode].DistanceFromStart = 0;
}
public IDictionary<string, double> CalculateDistances(Graph graph, string startingNode)
{
if (!graph.Nodes.Any(n => n.Key == startingNode))
throw new ArgumentException("Starting node must be in graph.");
InitialiseGraph(graph, startingNode);
ProcessGraph(graph, startingNode);
return ExtractDistances(graph);
}
public static void Main()
{
var graph = new Graph();
// Nodes
graph.AddNode("A");
graph.AddNode("B");
graph.AddNode("C");
graph.AddNode("D");
graph.AddNode("E");
graph.AddNode("F");
graph.AddNode("G");
graph.AddNode("H");
graph.AddNode("I");
graph.AddNode("J");
graph.AddNode("Z");
// Connections
graph.AddConnection("A", "B", 14, true);
graph.AddConnection("A", "C", 10, true);
graph.AddConnection("A", "D", 14, true);
graph.AddConnection("A", "E", 21, true);
graph.AddConnection("B", "C", 9, true);
graph.AddConnection("B", "E", 10, true);
graph.AddConnection("B", "F", 14, true);
graph.AddConnection("C", "D", 9, false);
graph.AddConnection("D", "G", 10, false);
graph.AddConnection("E", "H", 11, true);
graph.AddConnection("F", "C", 10, false);
graph.AddConnection("F", "H", 10, true);
graph.AddConnection("F", "I", 9, true);
graph.AddConnection("G", "F", 8, false);
graph.AddConnection("G", "I", 9, true);
graph.AddConnection("H", "J", 9, true);
graph.AddConnection("I", "J", 10, true);
var calculator = new DistanceCalculator();
var distances = calculator.CalculateDistances(graph, "G"); // Start from "G"
foreach (var d in distances)
{
Console.WriteLine("{0}, {1}", d.Key, d.Value);
}
}
private void ProcessGraph(Graph graph, string startingNode)
{
bool finished = false;
var queue = graph.Nodes.Values.ToList();
while (!finished)
{
Node nextNode = queue.OrderBy(n => n.DistanceFromStart).FirstOrDefault(
n => !double.IsPositiveInfinity(n.DistanceFromStart));
if (nextNode != null)
{
ProcessNode(nextNode, queue);
queue.Remove(nextNode);
}
else
{
finished = true;
}
}
}
private IDictionary<string, double> ExtractDistances(Graph graph)
{
return graph.Nodes.ToDictionary(n => n.Key, n => n.Value.DistanceFromStart);
}