It focuses on techniques more than memorizing theorems — e.g., invariants, extremal principle, parity arguments, coloring proofs.
Once you finish this book comfortably, move to: a mathematical olympiad primer
Leo closed the book. The title stared back at him: A Mathematical Olympiad Primer . It focuses on techniques more than memorizing theorems — e
Over the next few weeks, Leo treated the Primer less like a reference guide and more like a wise elder. The book was divided into the pillars of the Olympiad: Algebra, Combinatorics, Number Theory, and Geometry. a mathematical olympiad primer