This is a simple example implementing most classes you need in order to do project 3 in FYS3150/FYS4150.
You will need to implement the force calculation in solarsystem.cpp and a new class, the Velocity verlet integrator.
By default, the example prints all positions every timestep to a file called positions.xyz. You can visualize this by using i.e. Ovito.
Good luck :D