  We study the truck-drone cooperative delivery problem in a setting where a
single truck carrying a drone travels at constant speed on a straight-line
trajectory/street. Delivery to clients located in the plane and not on the
truck's trajectory is performed by the drone, which has limited carrying
capacity and flying range, and whose battery can be recharged when on the
truck. We show that the problem of maximizing the number of deliveries is
strongly NP-hard even in this simple setting. We present a 2-approximation
algorithm for the problem, and an optimal algorithm for a non-trivial family of
instances.
