21 lines
489 B
Haskell
21 lines
489 B
Haskell
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import Data.List
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upper = 10000
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isPrime :: Int -> Bool
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isPrime x = null [k | k <- [2..x-1], k * k <= x, x `mod` k == 0]
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primes = [x | x <- [2..upper], isPrime x]
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isPrimeNew :: Int -> Bool
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isPrimeNew x
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| x <= upper = elem x primes
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| otherwise = isPrime x
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isPrimePair :: Int -> Int -> Bool
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isPrimePair a b = isPrime(read(show a ++ show b)) && isPrime(read(show b ++ show a))
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primePairs = [(a, b) | a <- primes, b <- primes, a < b, isPrimePair a b]
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main = print primePairs
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