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36 lines
1.1 KiB
Racket
36 lines
1.1 KiB
Racket
5 years ago
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#lang br
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(require racket/file rackunit racket/sequence)
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(define pixel-data (for/list ([c (in-string (file->string "08.rktd"))])
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(string->number (string c))))
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(define img-width 25)
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(define img-height 6)
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(define layers (for/list ([layer (in-slice (* img-width img-height) pixel-data)])
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layer))
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(define ((digit-count digit) layer)
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(for/sum ([x (in-list layer)]
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#:when (= x digit))
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1))
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(define least-zero-layer (argmin (digit-count 0) layers))
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;; 1
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(check-eq?
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(* ((digit-count 1) least-zero-layer) ((digit-count 2) least-zero-layer))
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2286)
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(define (sum-pixels . ps)
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(for/first ([p (in-list ps)]
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#:when (< p 2))
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p))
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(define (layer->string layer)
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(string-join (for/list ([row (in-slice img-width layer)])
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(string-join (for/list ([digit (in-list row)])
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(if (zero? digit) " " "X")) "")) "\n"))
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;; 2
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(check-equal? (layer->string (apply map sum-pixels layers))
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" XX XX XXXX X XXX \nX X X X X X X \nX X X X X X \nX X X X XXX \nX X X X X X X \n XX XX XXXX XXXX X ")
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