public Dictionary <int, DistanceInfo> BuildDistanceTable(GraphDS graph, int source)
{
Dictionary <int, DistanceInfo> distanceMap = new Dictionary <int, DistanceInfo>();
Queue <int> queue = new Queue <int>();
queue.Enqueue(source);
for (int i = 0; i < graph.Numvertices; i++)
{
distanceMap.Add(i, new DistanceInfo());
}
distanceMap[0].SetDisance(0);
distanceMap[0].SetLastVertex(source);
while (queue.Count > 0)
{
var vertex = queue.Dequeue();
var adjacentList = graph.GetAdjacentVertices(vertex);
var distanceInfo = distanceMap[vertex];
foreach (var adjacent in adjacentList)
{
var currentDistance = distanceMap[adjacent].GetDistance();
if (currentDistance == -1)
{
distanceMap[adjacent].SetDisance(distanceInfo.GetDistance() + 1);
distanceMap[adjacent].SetDisance(distanceInfo.GetLastVertex());
if (graph.GetAdjacentVertices(adjacent).Count > 0)
{
queue.Enqueue(vertex);
}
}
}
}
return(distanceMap);
}
public List <int> ShortestPath(GraphDS graph, int source, int destination)
{
Dictionary <int, DistanceInfo> distanceMap = BuildDistanceTable(graph, source);
Stack <int> shortestPathStack = new Stack <int>();
shortestPathStack.Push(destination);
var lastVertex = distanceMap[destination].GetLastVertex();
while (lastVertex != -1 && lastVertex != source)
{
shortestPathStack.Push(lastVertex);
lastVertex = distanceMap[lastVertex].GetLastVertex();
}
if (lastVertex == -1)
{
return(null);
}
return(shortestPathStack.ToList());
}
