I am wondering what physics book(s)with relatively complex problems (undergrad/olympiad level), I've read "Fundamentals of Physics by Halliday and Resnick" and I found the problems to be fairly straightforward and not so challenging. for context I am a high school student and I've finished the physics curriculum in my school, also I am studying calculus 1 (Larson's calc book w/ prof leonard videos) and linear algebra (Gilbert Strang's book w/ khan academy linear algebra), I figured learning physics w/ calculus might help me understand calculus better since I am interested in physics, albeit I haven't touched multivariable calc yet (books for multivariable calc?). thanks, guys!