Optaplanner take fastest path

Question

• How can we optimize Optaplanner to select the fastest route? See the highlighted point in the below image. It is taking the long route.

Note: Vehicles does not need to come back depot. I think i cannot use CVRPTW as arrivalAfterDueTimeAtDepot is a build-in hard constraint (and besides i do not have any time constraints).

• How can we write a constraint to select the less capacity vehicle?
  For example, A customer needs only 3 items and we have two vehicles with 4 and 9 capacities. Seems like Optaplanner is selecting the first vehicle from the order of input by default.

Answer 1

I presume it's taking the blue vehicle for the center of Bengaluru because the green in is already at full capacity.

Check what the score is (calculated through Solver.getScoreDirectorFactory()) if you manually put that location in the green trip and swap the vehicles of the green and blue trip. If it's worse (or breaks a hard constraint), then it's normal that OptaPlanner selects the other solution. In that case, either your score function has bug (or you realize don't want that solution at all). But if it has indeed a better score, OptaPlanner's <localSearch> (such as Late Acceptance) should find it (especially when scaling out because ironically local optima are a bigger problem when scaling down). You can try to add <subchainSwapMoveSelector> etc to escape local optima faster.

If you want to guide the search more (which is often not a good idea), you can define a planning value strength comparator to sort small vehicles before big vehicles and use the Construction Heuristic WEAKEST_FIT(_DECREASING).