Extracting the root vertex when consulting the index

[mhnamaki]

Dear Takuya Akiba, I'm a fan of pruned-landmark-labeling since it can really execute on large graphs and provide fast and exact querying distances.

Recently, for one of my project, I had to modify the code to satisfy my new requirements. However, in "QueryDistance" function and at the following line, I need to know what is the root node (u) we ask the distance between s,t from. int td = idx_v.bpspt_d[i] + idx_w.bpspt_d[i];

My question is that, how can I extract this u : \delta = d_G(s,u) + d_G(u,t). In a higher level, I do not want to allow distance_querying uses some of the dummy nodes that I have added to the graph.

I appreciate any help on this. Thanks :).