Mastodawn

@blinry and I are still trying to solve last year's #adventOfCode. We're stuck on day 10, and we're out of ideas – except using linear optimization algorithms, but that feels like overkill... Has anyone of you solved day 10 and has a tip for us – do we really need to implement linear optimization?
https://en.wikipedia.org/wiki/Linear_programming#Integer_unknowns

Please use a spoiler for your answers ^^'

#AOC25 #advent_of_code #adventofcode2025 #adventofcode2025day10

Linear programming - Wikipedia

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Kata 📎Apr 14

@piko @blinry I haven’t found a great solution myself, but I have this link in my notes of someone who used some DFS thingy:

https://old.reddit.com/r/adventofcode/comments/1pity70/2025_day_10_solutions/ntb36sb/

I did not dig through this at all (it’s still on the “TODO later” list 😅), so I can’t vouch for it. Still, maybe you two can get some useful pointers here … ?

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Tim Holyoake Apr 14

@piko @blinry You can see my scruffy handwritten notes on an approach here https://z80.timholyoake.uk/advent-of-code-2025-in-fortran-77-mostly/ along with a link to my repository with my final version in it. It's written in fixed width Fortran, but uses recursion, so is a bit of a hybrid between legacy and modern Fortran! It should be relatively readable though as the final code includes comments.

Advent of Code 2025 in Fortran 77 (mostly) – retrocomputing ephemera

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fiveop Apr 14

@piko @blinry https://en.wikipedia.org/wiki/Dynamic_programming#Mathematical_optimization Linear optimization is probably overkill for part 1

Dynamic programming - Wikipedia

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DarkDust Apr 14

@piko @blinry I first solved part 2 with a recursive algorithm. After some optimisations it found the solution in 16min (Rust). Then I learned about Z3, which a lot of people used, which actually was quite interesting. This solution solves part 2 in less than a second, of course.

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