Concatenate two primes is also prime: Difference between revisions
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Found 128 such concatenated primes. |
Found 128 such concatenated primes. |
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</pre> |
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=={{header|Haskell}}== |
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<lang haskell>import Control.Applicative |
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import Data.List ( sort ) |
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import Data.List.Split ( chunksOf ) |
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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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solution :: [Int] |
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solution = sort $ filter isPrime $ map read ( (++) <$> numberlist <*> numberlist ) |
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where |
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numberlist :: [String] |
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numberlist = map show $ filter isPrime [1 .. 99] |
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main :: IO ( ) |
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main = do |
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mapM_ print $ chunksOf 15 solution</lang> |
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{{out}} |
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<pre> |
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[23,37,53,73,113,137,173,193,197,211,223,229,233,241,271] |
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[283,293,311,313,313,317,317,331,337,347,353,359,367,373,373] |
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[379,383,389,397,433,523,541,547,571,593,613,617,673,677,719] |
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[733,743,761,773,797,797,977,1117,1123,1129,1153,1171,1319,1361,1367] |
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[1373,1723,1741,1747,1753,1759,1783,1789,1913,1931,1973,1979,1997,2311,2341] |
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[2347,2371,2383,2389,2917,2953,2971,3119,3137,3167,3719,3761,3767,3779,3797] |
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[4111,4129,4153,4159,4337,4373,4397,4723,4729,4759,4783,4789,5323,5347,5923] |
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[5953,6113,6131,6143,6173,6197,6719,6737,6761,6779,7129,7159,7331,7919,7937] |
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[8311,8317,8329,8353,8389,8923,8929,8941,8971,9719,9743,9767] |
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</pre> |
</pre> |
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