What do I need to know for the 1800 CP-31 sheet?
Dijkstra, DSU, segment trees, modular inverses and nCr, and comfortable DP. The sheet assumes all of those and tests whether you can see when to use them.
All sheets
Priyansh Agarwal
1800: CP-31 Sheet
Curated by Priyansh Agarwal, ICPC World Finalist and AIR 1 in Google Kick Start, this sheet features all essential 1800 -rated Codeforces questions. With a Master (India Rank 34) on Codeforces and 4000+ students taught, Priyansh’s expertise ensures that this sheet will help you sharpen your competitive programming skills and make steady progress
31 problemscompetitive
Who the 1800 rated sheet is for
1800 on Codeforces is Expert level. Experts close to Candidate Master who solve Div. 2 D sometimes and want it consistently.
What these problems lean on: Advanced DP, Graph algorithms (Dijkstra, DSU), Combinatorics with modular inverse, Segment trees, Game theory.
The usual wall at 1800: Knowing the algorithm is assumed; the problem is reducing the statement to it. Most of the time spent is on modelling, not coding.
How to practise it: Give each problem an honest hour before the editorial. When you do read it, look for the reduction step you missed and not just the final algorithm.
0%
0/31
Overall progress
0 / 31
0/31
Hard
| Status | Problem | Solve | Practice | Revision | Level | |
|---|---|---|---|---|---|---|
| 1. | Gerrymandering |  | Hard | |||
| 2. | Rendez-vous de Marian et Robin | | Hard | |||
| 3. | Money Buys Happiness | | Hard | |||
| 4. | Exam in MAC | | Hard | |||
| 5. | Bicycles | | Hard | |||
| 6. | Kim's Quest | | Hard | |||
| 7. | LuoTianyi and the Floating Islands (Easy Version) | | Hard | |||
| 8. | A Wide, Wide Graph | | Hard | |||
| 9. | Friendly Spiders | | Hard | |||
| 10. | Lucky Permutation | | Hard | |||
| 11. | Sheikh (Easy version) | | Hard | |||
| 12. | Moving Both Hands | | Hard | |||
| 13. | Recover an RBS | | Hard | |||
| 14. | Max GEQ Sum | | Hard | |||
| 15. | Explorer Space | | Hard | |||
| 16. | The Sports Festival | | Hard | |||
| 17. | Zookeeper and The Infinite Zoo | | Hard | |||
| 18. | Road Reform | | Hard | |||
| 19. | Apollo versus Pan | | Hard | |||
| 20. | The Treasure of The Segments | | Hard | |||
| 21. | Catching Cheaters | | Hard | |||
| 22. | Identify the Operations | | Hard | |||
| 23. | Chef Monocarp | | Hard | |||
| 24. | Maximum Distributed Tree | | Hard | |||
| 25. | Stoned Game | | Hard | |||
| 26. | Count Triangles | | Hard | |||
| 27. | Edge Weight Assignment | | Hard | |||
| 28. | Three Blocks Palindrome (hard version) | | Hard | |||
| 29. | Irreducible Anagrams | | Hard | |||
| 30. | Numbers on Tree | | Hard | |||
| 31. | Christmas Trees | | Hard |
Frequently asked
How many problems should I solve at 1800 before 1900?
Finishing most of the 31 with honest attempts is enough. Contests matter more than volume at this point — solve virtual rounds alongside the sheet.
Is there a PDF of 1800: CP-31 Sheet to download?
There is no PDF here, and you do not need one. All 31 problems are listed in full on this page, free and without an account — and unlike a PDF the list remembers what you have ticked off, so you are not re-reading a static file to work out where you stopped. Use your browser's print view if you want it on paper.
How do I track my progress on 1800: CP-31 Sheet?
Tick a problem on this page and it stays ticked. Progress saves in your browser straight away with no account, and the counts update per section so you can see which parts of 1800: CP-31 Sheet you have actually covered. Signing in with Google syncs it across devices.
How many problems are in 1800: CP-31 Sheet?
- Every one is listed on this page and tickable as you solve it.
How long does 1800: CP-31 Sheet take to complete?
At roughly 25 minutes a problem — reading it, solving it and writing the approach down — 31 problems is about 13 hours, or 1 weeks at ten hours a week. Treat that as a planning figure rather than a promise; the first pass through an unfamiliar topic is always slower.
Is the 1800: CP-31 Sheet tracker free?
Yes, completely, and no account is needed. There is no paid tier and nothing is held back — the sheet itself is by Priyansh Agarwal, and this is a free tracker for it.
Should I finish 1800: CP-31 Sheet or switch between sheets?
Finish one. Sheets overlap heavily, so working several in parallel mostly means re-solving the same problems while never completing a full topic sweep. If you are not sure this is the right one for the time you have, the sheet comparison page puts the options side by side with hour estimates.