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Advent of Code 2020 Day09 Dyalog APL
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| DAY09←⍎¨⊃⎕NGET'data/2020/day09.txt'1 | |
| Day09←{ | |
| (i s)←⍵ | |
| r←(i-24)+⍳25 ⍝ Considered range | |
| d←DAY09[r]+(¯1↑r)⊃DAY09 ⍝ Changed vals | |
| n←1⌽1⊖s ⋄ n[;24]←d ⋄ n[24;]←d ⍝ Update the sums cache. Also: new←25 25↑1 1↓cache | |
| (i+1) (n) | |
| } | |
| (i _)←Day09⍣{(i s)←⍺ ⋄ ~s∊⍨i⊃DAY09} 25 (∘.+⍨25↑DAY09) | |
| idx⊃DAY09 ⍝ part 1 | |
| win←part1{⍺∊⍵+/DAY09:⍵⋄⍵+1}⍣≡⊢2 | |
| i←part1⍳⍨win+/DAY09 | |
| (⌈/+⌊/)DAY09[i+⍳win] ⍝ part2 |
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The caching thing was probably not worth it.