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24 lines
756 B
Racket
24 lines
756 B
Racket
7 years ago
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#lang reader "../aoc-lang.rkt"
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(provide (rename-out [#%mb #%module-begin]))
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(define-macro (#%mb (STARS) (HEX ...) ...)
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#'(#%module-begin
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((if (eq? 'STARS '★) one-star two-star) (list HEX ...)) ...))
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(define origin '(0 0 0))
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(define ne '(1 0 -1)) (define sw '(-1 0 1))
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(define n '(0 1 -1)) (define s '(0 -1 1))
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(define nw '(-1 1 0)) (define se '(1 -1 0))
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(provide ne sw n s nw se)
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(define (dist h1 h2) (/ (apply + (map abs (map - h1 h2))) 2))
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(define (one-star hexes) (dist origin (apply map + hexes)))
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(define (two-star hexes)
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(for/fold ([sum origin]
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[max-dist 0]
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#:result max-dist)
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([h (in-list hexes)])
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(define this-sum (map + h sum))
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(values this-sum (max max-dist (dist origin this-sum)))))
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