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#lang racket
(require "../../jj-aoc.rkt"
threading
racket/struct)
(struct present (l w h) #:transparent)
(define presents
(for/list ([size-string (in-lines (open-day 2 2015))])
(~> size-string (string-split "x") (map string->number _) (apply present _))))
;; part 1
(define (paper-area p)
(define main-area (~> p struct->list (combinations 2) (map (λ~> (apply * 2 _)) _) (apply + _)))
(define slack-area (~> p struct->list (sort <) (take 2) (apply * _)))
(+ main-area slack-area))
(for/sum ([p (in-list presents)]) (paper-area p))
;; part 2
(define (ribbon-length p)
(define ribbon-around-box (~> p struct->list (sort <) (take 2) (map (λ~> (* 2)) _) (apply + _)))
(define ribbon-for-bow (~> p struct->list (apply * _)))
(+ ribbon-around-box ribbon-for-bow))
(for/sum ([p (in-list presents)]) (ribbon-length p))
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