8 lines
214 B
Scheme
8 lines
214 B
Scheme
; twice faster, testing only odd divisors
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(define (prime? n)
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(if (< n 4) (> n 1)
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(and (odd? n)
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(let loop ((k 3))
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(or (> (* k k) n)
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(and (positive? (remainder n k))
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(loop (+ k 2))))))))
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