Week 5 code dojo solution with @phasedchirp

Week5.ipynb

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       "4"
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    "\n",
    "import Data.List\n",
    "input = \"abba\"\n",
    "choose2 n = n*(n-1) `div` 2\n",
    "reduced input = let\n",
    "    substrings       = filter (/=\"\") $ concatMap tails $ inits input\n",
    "    sortedSubstrings = sort $ map sort substrings\n",
    "    counts           = map length $ group sortedSubstrings\n",
    "    in foldr (\\x y -> if x > 1 then y + choose2 x else y) 0 counts\n",
    "reduced \"abba\"\n",
    "\n",
    "\n",
    "reduced' = foldReduced . (length <$>) <$> group <$> sort . (sort <$>) . filter (/= \"\") . (>>= tails) . inits\n",
    "foldReduced = foldr (\\x y -> if x > 1 then y + choose2 x else y) 0\n",
    "\n",
    "\n",
    "reduced'' = let\n",
    "    notNull  = filter (/=\"\")\n",
    "    sorted   = (sort <$>)\n",
    "    mapGroup = (group <$>)\n",
    "    in sum. (( (foldReduced . (length <$>)). group <$>)) . group <$>\n",
    "  (sort . sorted . notNull . (>>= tails) . inits)\n",
    "\n",
    "reduced' \"abba\"\n",
    "reduced'' \"abba\""
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       "[3,2,2,6,3]"
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   "source": [
    "map reduced'' [\n",
    "  \"ifailuhkqq\",\n",
    "  \"hucpoltgty\",\n",
    "  \"ovarjsnrbf\",\n",
    "  \"pvmupwjjjf\",\n",
    "  \"iwwhrlkpek\"]"
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   "execution_count": 43,
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   "source": [
    "readN :: Int -> IO [String]\n",
    "readN 0 = return []\n",
    "readN n = do\n",
    "    s    <- getLine\n",
    "    rest <- readN $ n-1\n",
    "    return $ s:rest\n",
    "    \n",
    "main :: IO ()\n",
    "main = do\n",
    "    num    <- read <$> getLine :: IO Int\n",
    "    inputs <- readN num\n",
    "    let counts = map reduced inputs\n",
    "    mapM_ print counts"
   ]
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