13 lines
396 B
Haskell
13 lines
396 B
Haskell
-- Find the sum of the only eleven primes that are both truncatable from left
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-- to right and right to left.
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import Euler
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import Data.Array.Unboxed
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truncations n = map fromDigits $ filter (not . null) $ inits (toDigits n) ++ tails (toDigits n)
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isPrimeArr = isPrimeArray 1000000
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isPrime n = n >= 2 && isPrimeArr!n /= 0
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main = print $ sum $ take 11 $ filter (all isPrime . truncations) [11..]
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