如果不同的车辆在第二次旅行中访问目的地，则多程 vrp 中的惩罚 ORTOOLS

Question

I have implemented multitrip (Allow vehicles to visit a destination more than once) VRP using ortools. This has been done by duplicating nodes for destinations and introducing virtual depots with negative loads.

I want same vehicle to visit destinations in 2nd trip which visited that destination in 1st trip. This is a soft constraint and a penalty should be added in the objective function if not followed. How can we implement this?

Answer 1

  /// Adds a soft constraint to force a set of variable indices to be on the
  /// same vehicle. If all nodes are not on the same vehicle, each extra vehicle
  /// used adds 'cost' to the cost function.
  void AddSoftSameVehicleConstraint(const std::vector<int64_t>& indices,
                                    int64_t cost);

Reference

Using this, I think you can model your requirement.