Difference between revisions of "Anagrams"
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(updated to for 6.6.. minor cleanups.) |
Tomjaguarpaw (talk | contribs) (Deleting page that hasn't been updated for over 10 years) |
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| − | <haskell> |
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| − | module Main (main) where |
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| − | import System.Environment (getArgs) |
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| − | import Data.Char (toUpper,isAlpha) |
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| − | import Data.List (sortBy) |
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| − | import Data.Ord (comparing) |
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| − | import qualified Data.ByteString.Char8 as B |
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| − | |||
| − | data CharCount = CharCount !Char !Int deriving (Show, Eq) |
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| − | data WordData = WordData B.ByteString [CharCount] deriving (Show, Eq) |
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| − | |||
| − | main = do |
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| − | [n] <- getArgs |
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| − | wl <- B.readFile n |
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| − | user <- B.getLine |
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| − | let results = findAnagrams (makeWordList wl) (countChars user) |
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| − | B.putStr . B.unlines . map B.unwords $ results |
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| − | |||
| − | findAnagrams :: [WordData] -> [CharCount] -> [[B.ByteString]] |
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| − | findAnagrams [] _ = [] |
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| − | findAnagrams lst@((WordData bs cc):rest) qcc = |
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| − | case (qcc `minus` cc) of |
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| − | Nothing -> remaining |
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| − | Just [] -> [bs]:remaining |
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| − | Just x -> map ((:) bs) (findAnagrams lst x) ++ remaining |
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| − | where remaining = findAnagrams rest qcc |
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| − | |||
| − | minus :: (Monad m) => [CharCount] -> [CharCount] -> m [CharCount] |
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| − | minus x [] = return x |
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| − | minus [] _ = fail "can't subtract from empty" |
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| − | minus (lft@(CharCount c1 i1):xs) r@((CharCount c2 i2):ys) |
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| − | | (c1 == c2) && (i2 == i1) = xs `minus` ys |
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| − | | (c1 == c2) && (i2 < i1) = do rem <- xs `minus` ys |
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| − | return $! (CharCount c1 (i1 - i2)):rem |
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| − | | (c1 < c2) = do rem <- xs `minus` r |
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| − | return $! lft:rem |
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| − | | (c1 == c2) && (i2 > i1) = fail "right has more chars than left" |
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| − | | (c1 > c2) = fail "right has chars not in left" |
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| − | | otherwise = error "Bad condition" |
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| − | |||
| − | countChars :: B.ByteString -> [CharCount] |
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| − | countChars = map counts . B.group . B.sort . B.map toUpper . B.filter isAlpha |
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| − | where counts x = CharCount (B.head x) (B.length x) |
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| − | |||
| − | makeWordList :: B.ByteString -> [WordData] |
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| − | makeWordList = map (\w -> WordData w (countChars w)) . sortBy (flip (comparing B.length)) . B.words |
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| − | |||
| − | </haskell> |
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| − | |||
| − | [[Category:Code]] |
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