  In an optimal visiting problem, we want to control a trajectory that has to
pass as close as possible to a collection of target points or regions. We
introduce a hybrid control-based approach for the classic problem where the
trajectory can switch between a group of discrete states related to the targets
of the problem. The model is subsequently adapted to a mean-field framework to
study viability and crowd fluxes to model a multitude of indistinguishable
players.
