fgl VS aoc-2021

Your names are good, I reckon it is Martin Erwig's fgl stuff and Andrey Mokhov's algebraic-graphs that you have in mind.

I am about to start a new project in Haskell, model checking with (new) tree-like data structures. I think it is best to start building on a library such that i can already have elegant base functions, yet i am wondering what library is currently the standard? I read about fgl ( https://hackage.haskell.org/package/fgl ), yet it is a very old library.

Couple of approaches to graphs that are state-free: functional graphs and algebraic graphs

Using fgl but only as a data structure this time, with edge labels denoting whether the target is a big room. Not using any of its algorithms as it doesn't have anything built-in for "traversal with re-visiting".

For part 2, instead of trying to union-merge from the lowest points, I simply found all connected regions of <9. I say "simply" because I just threw things at fgl, but setting the graph up first took a bit of work. buildGr is fast but picky about the exact order things come in with.

Basic C# solution with a straightforward try-everything simulation. This one could've been called 50 Thousand Iterations Under the Sea

C# solution

C# solution, I keep letter pair counts in a square grid and a separate map for individual letter counts

C# solution with basic graph search. I track the step counts to each cave and decide which next caves to take based on them, and prune it after returning from a recursive call to SearchFrom

C# solution with a straightforward stack-based approach. I modeled sum types using abstract record on line 62 to handle the three different return values from the processing function

C# solution, simple flood-fill type algo. I found a use for C# 9.0's record types, explained in the blurb at the top of the file

C# solution with a manual deduction process (one of many possible no doubt) that I figured out in the hours after midnight, then I slept on it and it took all morning to actually code the thing, but I like the result. Again a sprinkling of LINQ makes it bearable to write and read

C# code tries all positions between first and last crab

C# solution same as most others but with a bit of LINQ

C# nothing noteworthy other than LINQ saving the day again