RosettaCodeData/Task/Find-the-missing-permutation/Haskell/find-the-missing-permutatio...

36 lines
529 B
Haskell

import Data.Char (chr, ord)
import Data.Bits (xor)
missingPerm :: [String] -> String
missingPerm = fmap chr . foldr (zipWith xor . fmap ord) [0, 0, 0, 0]
deficientPermsList :: [String]
deficientPermsList =
[ "ABCD"
, "CABD"
, "ACDB"
, "DACB"
, "BCDA"
, "ACBD"
, "ADCB"
, "CDAB"
, "DABC"
, "BCAD"
, "CADB"
, "CDBA"
, "CBAD"
, "ABDC"
, "ADBC"
, "BDCA"
, "DCBA"
, "BACD"
, "BADC"
, "BDAC"
, "CBDA"
, "DBCA"
, "DCAB"
]
main :: IO ()
main = putStrLn $ missingPerm deficientPermsList