There are numerous reasons why you may want to put a "penalty" cost on high mileage in a route solution. For example, there may be a desire to simply limit the amount of driving time, or a desire to keep all the vehicles in a solution near the same mileage. One way to achieve this is to apply higher costs when the vehicle mileage for any particular route passes certain thresholds. In cost2.cpp, vehicle costs are calculated from the length of the trip; longer trips result in higher costs.

The first step is to write a natural language description of the problem. The constraints and objectives for cost2.cpp are the same as for the PDP; in particular, the objective is to minimize the costs of the delivery of all the parcels. The difference in this lesson lies in the way the costs are calculated. In cost2.cpp, the cost is determined from the total length of the vehicle route, which then determines the value returned by the segmented function.