private void shortestPathRecur(List<E> edges, int v_a, int v_b) {
int k = backtrace[v_a][v_b];
if (k == -1) {
E edge = graph.getEdge(vertices.get(v_a), vertices.get(v_b));
if (edge != null) {
edges.add(edge);
}
} else {
shortestPathRecur(edges, v_a, k);
shortestPathRecur(edges, k, v_b);
}
}
private GraphPath<V, E> getShortestPathImpl(V a, V b) {
int v_a = vertices.indexOf(a);
int v_b = vertices.indexOf(b);
List<E> edges = new ArrayList<E>();
shortestPathRecur(edges, v_a, v_b);
// no path, return null
if (edges.size() < 1) {
return null;
}
double weight = 0.;
for (E e : edges) {
weight += graph.getEdgeWeight(e);
}
GraphPathImpl<V, E> path = new GraphPathImpl<V, E>(graph, a, b, edges, weight);
return path;
}