14 lines
392 B
Racket
14 lines
392 B
Racket
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#lang racket
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(require math/number-theory)
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(define (primes x) (filter prime? (range 2 (sqrt x))))
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(define (primefactors x primes)
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(if (prime? x)
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(list x)
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(if (zero? (remainder x (car primes)))
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(cons (car primes) (primefactors (quotient x (car primes)) primes))
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(primefactors x (cdr primes)))))
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(apply max (primefactors 600851475143 (primes 600851475143)))
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