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  1. import Data.Function
  2. import Data.List
  3. import Control.Arrow
  4.  
  5. digitToNumber :: Char -> Int
  6. digitToNumber = read . (:[])
  7.  
  8. quintuples (a:xs@(b:c:d:e:_)) = map digitToNumber [a,b,c,d,e] : quintuples xs
  9. quintuples _ = []
  10.  
  11. products = map (product &&& id)
  12.  
  13. solve = maximumBy (compare `on` fst) . products . quintuples
  14.  
  15. main = let (prod,nums) = solve digits
  16.        in do putStr "Maximum product is with "
  17.              putStr $ show nums
  18.              putStr " = "
  19.              putStrLn $ show prod
  20.  
  21. digits = concat [
  22.         "73167176531330624919225119674426574742355349194934",
  23.         "96983520312774506326239578318016984801869478851843",
  24.         "85861560789112949495459501737958331952853208805511",
  25.         "12540698747158523863050715693290963295227443043557",
  26.         "66896648950445244523161731856403098711121722383113",
  27.         "62229893423380308135336276614282806444486645238749",
  28.         "30358907296290491560440772390713810515859307960866",
  29.         "70172427121883998797908792274921901699720888093776",
  30.         "65727333001053367881220235421809751254540594752243",
  31.         "52584907711670556013604839586446706324415722155397",
  32.         "53697817977846174064955149290862569321978468622482",
  33.         "83972241375657056057490261407972968652414535100474",
  34.         "82166370484403199890008895243450658541227588666881",
  35.         "16427171479924442928230863465674813919123162824586",
  36.         "17866458359124566529476545682848912883142607690042",
  37.         "24219022671055626321111109370544217506941658960408",
  38.         "07198403850962455444362981230987879927244284909188",
  39.         "84580156166097919133875499200524063689912560717606",
  40.         "05886116467109405077541002256983155200055935729725",
  41.         "71636269561882670428252483600823257530420752963450"]
  42.  
Success #stdin #stdout 0.02s 6316KB
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Standard input is empty
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Maximum product is with [9,9,8,7,9] = 40824
https://ideone.com/q8OZNh
language:
Haskell (ghc 8.4.4)
created:
12 years ago
visibility:
public

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