12 lines
346 B
Racket
12 lines
346 B
Racket
#lang typed/racket
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(require math/number-theory)
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(: max-prime-factor (-> Integer (U False Integer)))
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(define (max-prime-factor x)
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(if (prime? x) x
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(for/or ((i (filter prime? (range 2 (ceiling (assert (sqrt x) real?)))))
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#:when (zero? (remainder x i)))
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(max-prime-factor (quotient x i)))))
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(max-prime-factor 600851475143) |