Lately, I’ve noticed I get stuck on problems that don’t follow any standard approach. The kind where you can’t rely on a known DS or algorithm and just have to figure something out on your own.

Most of these fall under constructive algorithms, math, or what people usually call ad hoc (even though CF doesn’t have that tag).

I’ve been trying to find a collection of such problems in the 2000–2400 range, ones that are based on creative construction, math reasoning, or just clever ideas that don’t come usually from standard known approaches.

You can drop your favorite problems or the challenging ones in the rating range and I would love to try. Some problems that i found challenging and liked:

2034E - Permutations Harmony

2162G - Beautiful Tree

1392E - Omkar and Duck

If you know a good resource for this, or have solved problems that fit this category, please share them in the comments. It’ll help me and others who are trying to get better at this type of problem.

Thanks.