Hello Codeforces,

I like to code. Entered CP in late 2026; I almost quit cuz it was too hard, but the stuff that's hard is always good.

Looking forward to participating in the Zonal Computing Olympiad (ZCO), the first stage for the Indian Computing Olympiad (ICO). Missing out on ZCO-2026 was a big shame for me, so I want to qualify in the upcoming year.

The Strat

The exam is held on CodeChef, so I'll start practising more there (forgive me, Mike) and, at the same time, write these blog posts to keep going!

• using the CSES problem set
• solving 1100- to 1300-rated CF problems (cuz for some reason these are just better structured)
• solving 1400- to 1500-rated CC problems
• fixing my contribution on CF (it's $$$ -25 $$$ )

Simple as that.

ZCO Blog 1 done!

Hello Codeforces,

i wondered why do alice and bob play such beautiful games which people can make questions out of!

Like, their games are astonishingly fun to read (and solve LOL)

here is a list of some of the games of alice and bob, and again, an important detail — they love to play them.

https://codeforces.me/problemset/problem/346/A

https://codeforces.me/problemset/problem/6/C

https://codeforces.me/problemset/problem/1373/B

https://codeforces.me/problemset/problem/1914/E2

https://codeforces.me/problemset/problem/1860/C

https://codeforces.me/problemset/problem/1704/F

https://codeforces.me/problemset/gymProblem/102392/I

https://codeforces.me/blog/entry/71272

https://codeforces.me/blog/entry/95663

https://codeforces.me/blog/entry/56477

https://codeforces.me/problemset/problem/2002/B

Keep playing those games Alice and Bob, we love them!

Hey Codeforces,

One thing that confused me early on: CF problem ratings aren't assigned by setters — they're crowd-sourced from contest performance. A problem rated 900 might have been solved by fewer people than an 800 in the same round, just because it appeared later in the standings. This means the raw rating is sometimes a poor proxy for actual learning difficulty, especially for beginners.

For example, some 900-rated problems require a clean observation you either see or you don't, while certain 800s are just tedious implementation with no real insight. For someone grinding Div 3/4, blindly following rating order can be discouraging or just inefficient.

I put together a curated problem sheet with this in mind: 70 problems across the 800–1000 range, ordered by what I'd call learning difficulty rather than raw CF rating. Each problem has a note explaining why it's placed where it is, and a Div 3/Div 4 badge so you know what type of contest it came from.

A preview

A few things that might be useful:

• Progress is saved via URL hash — just bookmark the link, no account needed
• There's a handle tracker: enter your CF handle and it auto-marks problems you've already AC'd
• The curation criteria page lists the 5 rules every problem must satisfy — if you think something doesn't belong, cite the rule and suggest a replacement via feedback
• 22 recommended Div 3/4 rounds are listed for when you're ready to test yourself under contest conditions

Link: cf-sheet.vercel.app

Happy to discuss the ordering choices or problem selection in the comments. If you think a specific problem is misplaced or shouldn't be there, I'm genuinely open to changes.