52 lines
1.5 KiB
Racket
52 lines
1.5 KiB
Racket
#lang curly-fn racket
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(require "scripts/aoc.rkt")
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;; solution for day 12
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;; helper functions here
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(define d->r degrees->radians)
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(define (part1 input)
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(define-values [dir s]
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(for/fold ([dir 0] [s 0]) ([ins (in-list input)])
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(match-define (cons ltr num) ins)
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(match ltr
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["N" (values dir (+ s (* +i num)))]
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["S" (values dir (- s (* +i num)))]
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["E" (values dir (+ s num))]
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["W" (values dir (- s num))]
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["L" (values (+ dir (d->r num)) s)]
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["R" (values (- dir (d->r num)) s)]
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["F" (values dir (+ s (make-polar num dir)))])))
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(inexact->exact (round (+ (abs (real-part s)) (abs (imag-part s))))))
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(define (part2 input)
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(define-values [s w]
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(for/fold ([s 0] [w 10+1i]) ([ins (in-list input)])
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(match-define (cons ltr num) ins)
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(match ltr
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["N" (values s (+ w (* +i num)))]
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["S" (values s (- w (* +i num)))]
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["E" (values s (+ w num))]
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["W" (values s (- w num))]
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["L" (values s (* w (make-polar 1 (d->r num))))]
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["R" (values s (* w (make-polar 1 (d->r (- num)))))]
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["F" (values (+ s (* w num)) w)])))
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(inexact->exact (round (+ (abs (real-part s)) (abs (imag-part s))))))
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(module+ main
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(define input
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(for/list ([line (in-list (file->lines "inputs/12"))])
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(match line
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[(pregexp #px"^(.)([0-9]+)$" (list _ dir (app string->number num)))
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(cons dir num)])))
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;; part 1
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(answer 12 1 (part1 input))
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;; part 2
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(answer 12 2 (part2 input))
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(displayln "meow"))
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