42 lines
1.5 KiB
Racket
42 lines
1.5 KiB
Racket
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(module assignment1 racket
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;question 1
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(define (drop-divisible divisor number-list)
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(filter (lambda (x)
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(or
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(not
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(eq? (modulo x divisor) 0))
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(eq? x divisor)))
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number-list))
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;question 2
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(define (sieve-with divisor-list number-list)
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(define (iter divs lst)
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(cond
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[(empty? divs) lst]
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[else (iter (rest divs) (drop-divisible (first divs) lst))]))
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(iter divisor-list number-list))
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;question 3
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(define (sieve potential-prime)
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;never need to check for primes below 2
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;you also never need to check for a number above the square root in a given range
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;plus one just for off by one errors
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(sieve-with (range 2 (+ (integer-sqrt potential-prime) 1)) (range 2 potential-prime)))
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(module+ test
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(require rackunit)
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(check-equal? (drop-divisible 2 (list 2 3 4 5 6 7 8 9 10)) (list 2 3 5 7 9))
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(check-equal? (drop-divisible 3 (list 2 3 4 5 6 7 8 9 10)) (list 2 3 4 5 7 8 10))
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(check-equal? (drop-divisible 5 (list 2 3 4 5 6 7 8 9 10)) (list 2 3 4 5 6 7 8 9))
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(check-equal? (sieve-with '(2 3) (list 2 3 4 5 6 7 8 9 10)) (list 2 3 5 7))
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(check-equal? (sieve-with '() (list 2 3 4 5 6 7 8 9 10)) (list 2 3 4 5 6 7 8 9 10))
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(check-equal? (sieve 10) (list 2 3 5 7))
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;question 4
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(require math/number-theory)
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(check-equal? (sieve 100) (filter prime? (range 1 100)))
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(check-equal? (sieve 100000) (filter prime? (range 1 100000)))
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))
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