discrete and combinatorics: a walk through combinatorics discrete math: an open introduction

Geometry: Baragar, Several USAMO and the high school tests, and imo geometry things. Computational geometry (need) todo. Trig and stuff like that. Tricks, yeah.

Number theory: Burton, imo, highschoool AMC stuff, hardy and wright

Algebra: There are imo practice books. Also, LADR, LADW, shit like that

Caculus: Stewart, shit like that idk if there are harder books