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33 lines
1.1 KiB
Racket
33 lines
1.1 KiB
Racket
8 years ago
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#lang br/quicklang ;; http://adventofcode.com/2016/day/22
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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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(let ([lines (string-split (port->string port) "\n")])
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#`(module mod "lang.rkt"
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#,@(for/list ([args (in-list (map string-split (cddr lines)))])
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`(node ,@args))))))
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(define-macro (mb . NODES)
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#'(#%module-begin
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(define nodes (list . NODES))
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(count-viable-pairs nodes)))
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(struct $node (pos used avail) #:transparent)
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(define-macro (node NAME _ USED AVAIL _)
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#'($node
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(apply (λ(r i) (+ (string->number r)
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(* (string->number i) +i))) (regexp-match* #px"\\d+" NAME))
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(string->number (string-trim USED "T"))
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(string->number (string-trim AVAIL "T"))))
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(provide node)
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(define (count-viable-pairs nodes)
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(for*/sum ([a (in-list nodes)]
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[b (in-list nodes)]
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#:when (and (not (zero? ($node-used a)))
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(not (equal? ($node-pos a) ($node-pos b)))
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(<= ($node-used a) ($node-avail b))))
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1))
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