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#lang racket
(require advent-of-code
threading)
(struct hand (cards wager) #:transparent)
(define/match (card->int card)
[((? char-numeric?)) (~> card string string->number)]
[(#\A) 14]
[(#\K) 13]
[(#\Q) 12]
[(#\J) 11]
[(#\T) 10]
[(#\*) 1])
(define (parse-hand str)
(match-define (list card-str wager-str) (string-split str))
(define cards (~> card-str string->list (map card->int _)))
(define wager (~> wager-str string->number))
(hand cards wager))
(define input (~> (open-aoc-input (find-session) 2023 7 #:cache #true) port->lines))
(define (identify-hand h)
(define freqs (~> h hand-cards (sort <) (group-by identity _) (map length _)))
(match freqs
[(list-no-order 5) 8]
[(list-no-order 1 4) 7]
[(list-no-order 2 3) 6]
[(list-no-order 1 1 3) 5]
[(list-no-order 1 2 2) 4]
[(list-no-order 1 1 1 2) 3]
[(list-no-order 1 1 1 1 1) 2]))
(define (compare-first-card cs1 cs2)
(if (= (first cs1) (first cs2))
(compare-first-card (rest cs1) (rest cs2))
(< (first cs1) (first cs2))))
(define (compare-hands h1 h2)
(define rank1 (identify-hand h1))
(define rank2 (identify-hand h2))
(if (= rank1 rank2) (compare-first-card (hand-cards h1) (hand-cards h2)) (< rank1 rank2)))
;; part 1
(for/sum ([(h i) (in-indexed (~> input (map parse-hand _) (sort compare-hands)))])
(* (add1 i) (hand-wager h)))
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