this post was submitted on 02 Dec 2024
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Advent of Code 2024 - Historian goes looking for history in all the wrong places (adventofcode.com)
submitted 2 days ago by Architeuthis@awful.systems to c/notawfultech@awful.systems
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copy pasting the rules from last year's thread:

Rules: no spoilers.

The other rules are made up aswe go along.

Share code by link to a forge, home page, pastebin (Eric Wastl has one here) or code section in a comment.

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[–] swlabr@awful.systems 2 points 15 hours ago (1 children)

4:

4-1I tried something clever and was punished for my hubris, but it turned out ok.

I treated the input as a list of strings and searched for "XMAS" and "SAMX", rotating and transposing the list to scan for vertical and diagonal words.

In my arrogance, I thought I could do the diagonal rotation easily, but I was very wrong. I got it out in the end, though.

4-2this was easier than 4-1. An O(n^2^) solution just scanning for X-MAS was good enough. Maybe there was a more clever solution that used, i dunno, string hashing or something but whatever.

[–] gerikson@awful.systems 2 points 12 hours ago (1 children)

re: 4-2

is it really n^2 tho? You have to do a constant check around each element, but that does not increase with the number of elements. And you can optimize a bit by marking already seen 'A's as illegal states and don't have to check them when the next row is processed.

[–] swlabr@awful.systems 2 points 12 hours ago

i am a simple manI see square input, i say n^2^