Merge pull request #3243 from stuart-little/stuart-little_059_haskell

1st commit on 059_haskell

1 files changed, 17 insertions, 0 deletions

diff --git a/challenge-059/stuart-little/haskell/ch-2.hs b/challenge-059/stuart-little/haskell/ch-2.hs
new file mode 100755
index 0000000000..1269923da7
--- /dev/null
+++ b/challenge-059/stuart-little/haskell/ch-2.hs
@@ -0,0 +1,17 @@
+#!/usr/bin/env runghc
+
+-- run <script> <space-separated numbers>
+
+import System.Environment (getArgs,)
+import Control.Monad (liftM,)
+import Data.Digits (digitsRev,)
+import Data.List (transpose,)
+import Data.List.Utils (countElem,)
+
+diffs :: Int -> [Int] -> Int
+diffs l xs = let (zeros,ones,lxs) = (countElem 0 xs,countElem 1 xs,length xs) in
+      div (l*(l-1) - ones*(ones - 1) - (zeros + l - lxs)*(zeros+l - lxs - 1)) 2
+
+main = do
+  nrs <- liftM (map (read::String->Int)) getArgs
+  print $ sum $ map (diffs $ length nrs) $ transpose $ map (digitsRev 2) nrs