Find squares n where n+1 is prime: Difference between revisions
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=={{header|Haskell}}== |
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<syntaxhighlight lang="haskell"> |
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module Squares |
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where |
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isPrime :: Int -> Bool |
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isPrime n |
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|n == 2 = True |
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|n == 1 = False |
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|otherwise = null $ filter (\i -> mod n i == 0 ) [2 .. root] |
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where |
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root :: Int |
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root = floor $ sqrt $ fromIntegral n |
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isSquare :: Int -> Bool |
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isSquare n = theFloor * theFloor == n |
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where |
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theFloor :: Int |
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theFloor = floor $ sqrt $ fromIntegral n |
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solution :: [Int] |
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solution = [d | d <- [1..999] , isSquare d && isPrime ( d + 1 )] |
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</syntaxhighlight> |
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{{out}} |
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<pre> |
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[1,4,16,36,100,196,256,400,576,676] |
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</pre> |
</pre> |
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