Advent of Code 2025 Day 4 (BaseA Style)

[AlteryxMatt]

Discussion thread for day 4 of the Advent of Code - https://adventofcode.com/2025/day/4

[PangHC]

Start to use back macros created in previous years.

Spoiler

[Qiu]

Everyone is so fast.

Spoiler

[DataNath]

The grids are back! For those of us who've participated in previous years, this is pretty much our bread and butter now, though today was definitely a very kind challenge compared to others! Workflow/macro aren't as clean as they could be but I was more than pleased with everything working first time.

Spoiler

[OllieClarke]

I went route 1 today

Spoiler

[DylanBell]

By far my favourite challenge so far!

[Kenda]

Spoiler

part 1 so far! definitely could've had a faster run time if I narrowed down the joins instead of appending everything, but it worked😂

[Goddenra]

Some very elegant solutions out there. Had to go down the macro route for Part 2 for reasons of sanity.

Spoiler

Got a bit stuck on Part 1, as missed a corner case with the boundaries which was careless. Annoyingly it said I had the same answer as someone else, so knew I was really close. Should tidy it up a bit really.

Haven't created an iterative macro in a little while, so AoC is always a good refresher ...

 

[mmontgomery]

Day  4

Spoiler

Had a dumb bug on P1 where I was filtering on adjoining points = '@' and counting vs just counting if they existed. Once I got that, P1 and P2 were a breeze.

P2 had the I macro using the same logic as P1 just adjusting for grid points with updated values

[Erin]

Shout out to @Carolyn - I have my first "Nope didn't work" container. We're supposed to be keeping those? Kinda glad I did because I went back later to figure out why it didn't work and of course it was a rookie mistake. Learning so much!

My overall strategy for Pt 1:

Spoiler

1. Split the data up and assign each single character coordinates.
2. Calculate what all the neighbor coordinates are.
3. Look up the neighbor character using the neighbor coordinates.
4. Count the number of neighbor rolls.
5. Filter for the answer. 

Well, I did do that more or less but my initial answer was too low. I kept getting the same answer too, so I decided to scrap it (but keep it?) and try a different way to lookup the values. This worked, and it turns out my first route didn't work because.... 

Spoiler

My filter excluded neighbors with a zero roll count. One little tweak there and the first route would've been fine.

Ah win some, learn some. 😁

 Then for Pt 2

Spoiler

I put Pt 1 in an iterative macro and updated the char to be a ".", then sent it back through for another go. Easy peasy.

[DavidP]

Thanks for the tip on the zero counts @Hub119 !

Spoiler

Spoiler