Putnam Warmups
A collection of short problems designed to build intuition in invariants, modular arithmetic, and combinatorics.
Start here
Open training guide →New to these problems? Begin with the guide. It shows how to start: experimenting, hunting invariants, and what to do when you’re stuck.
- 1. Parity invariant warmupDifficulty 2
- 2. A modular invariant warmupDifficulty 3
- 3. A pigeonhole principle warmupDifficulty 3