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#lang racket
(require advent-of-code
threading)
(define calibration-values (fetch-aoc-input (find-session) 2023 1))
(define (to-number str)
(match (string->number str)
[#false (hash-ref word-to-digit str)]
[n n]))
(define (parse-calibration-value v valid)
(for/fold ([acc '()] [value v] #:result (+ (to-number (first acc)) (* 10 (to-number (last acc)))))
([_ (in-naturals)])
#:break (equal? value "")
(let ([possible-prefix (findf (curry string-prefix? value) valid)])
(if possible-prefix
(values (cons possible-prefix acc) (substring value 1))
(values acc (substring value 1))))))
(define (total-calibration input valid)
(~> input
(string-trim)
(string-split "\n")
(map (λ~> (parse-calibration-value valid)) _)
(apply + _)))
;; part 1
(define valid-for-part-1 (~> (range 1 10) (map ~a _)))
(total-calibration calibration-values valid-for-part-1)
;; part 2
(define word-to-digit
(hash "one" 1 "two" 2 "three" 3 "four" 4 "five" 5 "six" 6 "seven" 7 "eight" 8 "nine" 9))
(define valid-for-part-2 (append valid-for-part-1 (hash-keys word-to-digit)))
(total-calibration calibration-values valid-for-part-2)
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