here are some of my favorite OI problems!
IOI
- 2020 comparing plants (great writeup by ecnerwala here)
- 2017 ancient books
- 2017 simurgh
- 2015 sorting
- 2018 seats
- 2018 highway tolls
- 2018 werewolf
- mechanical doll
- 2020 stations
- 2016 detecting molecules
JOI
- Designated Cities
- Dungeon 3
- Sandcastle 2
- JOI Lamps
- Two Dishes
- Sightseeing in Kyoto (https://qoj.ac/problem/3502); kinda related to green’s theorem?
CF
- 2147F: Exchange Queries
- 2223D: Zhily and Cycle
- 2229F: Load Unbalancing
- cake is a lie (fun extended euclidean algo problem)
- 2006C: Eri and Expanded Sets
- 1943D: Counting is Fun
- Hanabi
Misc.
- Gesture Password: you are given a weighted tree. in one operation, you may pick a path of nodes and decrement the weights of all those nodes. what’s the minimum number of operations to reduce all weights to EXACTLY 0?
Simple
These are “simpler” problems that are still quite fun to think about.