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#lang racket
(require advent-of-code
threading)
(define fuel-requirements (port->lines (open-aoc-input (find-session) 2022 25 #:cache #true)))
(define (snafu->decimal snafu)
(for/sum ([digit (in-list (~> snafu string->list reverse))] [place (in-naturals)])
(define value
(match digit
[#\= -2]
[#\- -1]
[c (~> c string string->number)]))
(* value (expt 5 place))))
(define (decimal->snafu n [acc '()])
(match n
[0 (list->string acc)]
[n (decimal->snafu (quotient (+ n 2) 5) (cons (string-ref "012=-" (modulo n 5)) acc))]))
;; part 1
(~> (for/sum ([fuel (in-list fuel-requirements)]) (snafu->decimal fuel)) decimal->snafu)
;; no part 2 メリークリスマス
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