September 2017 Update

Task/ABC-Problem/Haskell/abc-problem-1.hs

@@ -0,0 +1,15 @@
+import Data.List (delete)
+import Data.Char (toUpper)
+
+-- returns list of all solutions, each solution being a list of blocks
+abc :: (Eq a) => [[a]] -> [a] -> [[[a]]]
+abc _ [] = [[]]
+abc blocks (c:cs) = [b:ans | b <- blocks, c `elem` b,
+                             ans <- abc (delete b blocks) cs]
+
+blocks = ["BO", "XK", "DQ", "CP", "NA", "GT", "RE", "TG", "QD", "FS",
+          "JW", "HU", "VI", "AN", "OB", "ER", "FS", "LY", "PC", "ZM"]
+
+main :: IO ()
+main = mapM_ (\w -> print (w, not . null $ abc blocks (map toUpper w)))
+         ["", "A", "BARK", "BoOK", "TrEAT", "COmMoN", "SQUAD", "conFUsE"]