/**
* Calculate the distance from the target vertex to the input
* vertex using forward star form.
* (FLOWER)
*
* @param vertex
*/
public Path UpdateCostForward(BaseVertex vertex)
{
double cost = Graph.DISCONNECTED;
// 1. get the set of successors of the input vertex
ISet <BaseVertex> adjVertexSet = graph.GetAdjacentVertices(vertex);
// 2. make sure the input vertex exists in the index
if (!startVertexDistanceIndex.ContainsKey(vertex))
{
startVertexDistanceIndex.Add(vertex, Graph.DISCONNECTED);
}
// 3. update the distance from the root to the input vertex if necessary
foreach (BaseVertex curVertex in adjVertexSet)
{
// 3.1 get the distance from the root to one successor of the input vertex
double distance = startVertexDistanceIndex.ContainsKey(curVertex)?
startVertexDistanceIndex[curVertex] : Graph.DISCONNECTED;
// 3.2 calculate the distance from the root to the input vertex
distance += graph.GetEdgeWeight(vertex, curVertex);
//distance += ((VariableGraph)graph).get_edge_weight_of_graph(vertex, curVertex);
// 3.3 update the distance if necessary
double costOfVertex = startVertexDistanceIndex[vertex];
if (costOfVertex > distance)
{
startVertexDistanceIndex.AddOrReplace(vertex, distance);
predecessorIndex.AddOrReplace(vertex, curVertex);
cost = distance;
}
}
// 4. create the subPath if exists
Path subPath = null;
if (cost < Graph.DISCONNECTED)
{
subPath = new Path();
subPath.SetWeight(cost);
java.util.LinkedList <BaseVertex> vertexList = subPath.GetVertexList();
vertexList.add(vertex);
BaseVertex selVertex = predecessorIndex[vertex];
while (selVertex != null)
{
vertexList.add(selVertex);
selVertex = predecessorIndex.GetValueIfExists(selVertex);
}
}
return(subPath);
}
