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39 lines
1017 B
Racket
39 lines
1017 B
Racket
#lang br/quicklang ;; http://adventofcode.com/2016/day/16
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(require openssl/md5)
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(provide read-syntax
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(rename-out [mb #%module-begin]))
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(define (read-syntax path port)
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(strip-bindings
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#`(module mod "lang.rkt"
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#,@(string-split (string-trim (port->string port)) ", "))))
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(define-macro (mb SIZE INIT)
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#'(#%module-begin
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(display (list->string (checksum (fill-disk (string->list INIT) (string->number SIZE)))))))
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(define (dragonize cs)
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(append cs '(#\0)
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(for/list ([c (in-list (reverse cs))])
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(if (eqv? c #\1)
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#\0
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#\1))))
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(define (fill-disk init size)
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(let loop ([cs init])
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(if (>= (length cs) size)
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(take cs size)
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(loop (dragonize cs)))))
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(require sugar/list)
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(define (checksum cs)
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(let loop ([cs cs])
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(if (odd? (length cs))
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cs
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(loop
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(for/list ([match (in-list (slice-at cs 2))])
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(if (member match '((#\0 #\0) (#\1 #\1)))
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#\1
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#\0))))))
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