Day 8: Haunted Wasteland

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[-] corristo@programming.dev 3 points 2 years ago* (last edited 2 years ago)

APL

I'm using this year's AoC to learn (Dyalog) APL, so this is most likely a pretty terrible solutions. I would've liked to use ⍣ instead of of my imitation of a while loop with a recursive function, but I couldn't figure out how to get to the number of iterations ⍣ performed to arrive at the destination. If someone here knows how to do that (or has other suggestions for improvement) I'm open for suggestions.

⎕IO ← 0       ⍝ use 0-based indexes
I←⌷⍨∘⊃⍨⍤0 99  ⍝ "sane" indexing
⎕PP←17        ⍝ print integers with up to 17 significant digits without use of scientific notation

input←⊃⎕NGET'inputs/day8.txt'1
instructions←⊃input
p←↑{0 2 4 I{6⍴⎕CSV⍠'Widths'(3 4 3 2 3 1)⊢⍵'S'1}⍵}¨ 2↓input
nodes←,1↑[1]p
L←(⍳⍴nodes) ∘.{nodes[⍺]≡⍵ 1 ⌷p} ⍳⍴nodes
R←(⍳⍴nodes) ∘.{nodes[⍺]≡⍵ 2 ⌷p} ⍳⍴nodes
S←(⊃(+.×)/{'R'≡⍵:R ⋄ ⍵≡'L':L}¨⌽instructions)
⎕←(≢instructions) × {⍺←0 ⋄ ⍵[⍸'ZZZ'∘≡¨nodes]: ⍺ ⋄ ⍺+1 ∇ S+.×⍵}'AAA'∘≡¨nodes                             ⍝ part 1
⎕←∧/(≢instructions) × {⍺←0 ⋄ 0≡+/⍵[⍸~('Z'∘=⊢/)¨nodes]: ⍺ ⋄ ⍺+1 ∇ S+.×⍵}¨{(⍳≢nodes)=⍵}¨⍸('A'∘=⊢/)¨nodes  ⍝ part 2

this post was submitted on 08 Dec 2023

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