1st commit on 007_haskell

2 files changed, 34 insertions, 0 deletions

diff --git a/challenge-007/stuart-little/haskell/ch-1.hs b/challenge-007/stuart-little/haskell/ch-1.hs
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+++ b/challenge-007/stuart-little/haskell/ch-1.hs
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+#!/usr/bin/env runghc
+
+-- run <script>
+
+main = do
+  mapM_ print $ let digSum x = sum $ map (\d-> read [d]::Int) $ show x in (0:) $ filter (\x -> mod x (digSum x) == 0) [1..50]
diff --git a/challenge-007/stuart-little/haskell/ch-2.hs b/challenge-007/stuart-little/haskell/ch-2.hs
new file mode 100755
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+++ b/challenge-007/stuart-little/haskell/ch-2.hs
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+#!/usr/bin/env runghc
+
+-- run <script> <word1> <word2> <path-to-file>
+
+import System.Environment (getArgs,)
+import Data.List (delete,)
+import Data.List.Extra (minimumOn,notNull,)
+import Math.TreeFun.Tree (boolToInt,)
+import Control.Monad (liftM,)
+
+dist1 :: Eq a => [a] -> [a] -> Bool
+dist1 xs ys = ((length xs) == (length ys)) && ((==) 1 $ sum $ map boolToInt $ zipWith (/=) xs ys)
+
+shortestLadder :: String -> String -> [String] -> [String]
+shortestLadder w1 w2 ws
+  |(notElem w1 ws) || (notElem w2 ws) =[]
+  |w1 == w2 =[w1]
+  |otherwise = let
+     wsshort = delete w1 ws
+     l = map (w1:) $ filter (notNull) $ map (\w -> shortestLadder w w2 wsshort) $ filter (dist1 w1) wsshort
+   in
+     if (null l) then []
+     else (minimumOn length l)
+     
+main = do
+  (w1:w2:file:_) <- getArgs
+  ws <- liftM words $ readFile file
+  putStrLn $ unwords $ shortestLadder w1 w2 ws