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49 lines
1.5 KiB
Racket
49 lines
1.5 KiB
Racket
#lang debug br
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(require racket/file racket/set)
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(define fp (open-input-file "05.txt"))
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(define fpbs (port->bytes fp))
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(define-macro (for/mutable-list (SEQ ...) . BODY)
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#'(let loop ([mprs null][xs (reverse (for/list (SEQ ...) . BODY))])
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(if (empty? xs)
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mprs
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(loop (mcons (car xs) mprs) (cdr xs)))))
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(define (reactive-pair? mprs)
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(= 32 (abs (- (mcar (mcdr mprs)) (mcar (mcdr (mcdr mprs)))))))
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(define (react [fpbs fpbs])
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(define mprs0 (mcons #f (for/mutable-list ([b (in-bytes fpbs)])
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b)))
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(let loop ([mprs mprs0][found? #false])
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(cond
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[(or (empty? mprs)
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(empty? (mcdr mprs))
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(empty? (mcdr (mcdr mprs))))
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(if found? (loop mprs0 #false) mprs0)]
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[(reactive-pair? mprs)
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(set-mcdr! mprs (mcdr (mcdr (mcdr mprs))))
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(loop (mcdr mprs) #true)]
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[else (loop (mcdr mprs) found?)]))
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(for/sum ([val (in-mlist (mcdr mprs0))])
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1))
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(define (★)
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(react fpbs))
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(define possible-units
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(map char->integer (remove-duplicates (map char-upcase (map integer->char (bytes->list fpbs))) char=?)))
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(define (remove-unit fbps unit)
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(regexp-replace* (regexp (format "[~a~a]" (integer->char unit) (integer->char (+ unit 32)))) fbps ""))
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(define (★★)
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(apply min (for/list ([unit (in-list possible-units)])
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(react (remove-unit fpbs unit)))))
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(module+ test
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(require rackunit)
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(check-equal? (time (★)) 10564)
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(check-equal? (time (★★)) 6336)) |