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20 lines
687 B
Racket
20 lines
687 B
Racket
4 years ago
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#lang br
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(require racket/file rackunit)
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(define (trees-in-slope horiz vert)
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(for/fold ([mod 0]
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[sum 0]
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#:result sum)
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([(ln lidx) (in-indexed (file->lines "03.rktd"))]
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#:when (zero? (modulo lidx vert)))
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(values (+ mod horiz)
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(if (char=? #\# (string-ref ln (modulo mod (string-length ln)))) (add1 sum) sum))))
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(check-equal? (trees-in-slope 3 1) 151)
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(check-equal? (apply * (list
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(trees-in-slope 1 1)
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(trees-in-slope 3 1)
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(trees-in-slope 5 1)
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(trees-in-slope 7 1)
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(trees-in-slope 1 2))) 7540141059)
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