best books of Physics Olympiad
If you ae preparing for Olympiads from physics then you can go with the Mtg Olympiad books or PEARSON IIT FOUNDATION PHYSICS BOOK ( If you are below 11th class ).
Also if you are in 11th or 12th then for Olympiad and for other competitive books cengage physics is best.
You will get a lot of solved examples from easy to hard level and you will get a lot of practice questions too.
And for more objective practice refer Arihant Olympiad book for Nsep or Inpho for extreme practice.