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  1. tokenize "" = ["epsilon"]
  2. tokenize (':':x:xs) =
  3.     case x of
  4.         ')' -> "smiley" : (tokenize xs)
  5.         '(' -> "frowney" : (tokenize xs)
  6.         _   -> "ignored" : (tokenize xs)
  7.  
  8.  
  9. tokenize ('(':xs) = "left_paren" : (tokenize xs)
  10. tokenize (')':xs) = "right_paren" : (tokenize xs)
  11. tokenize (x:xs) = "ignored" : (tokenize xs)
  12.  
  13. parseParens stack (tok:tokens) = 
  14.     case tok of
  15.         "left_paren" -> parseParens ("left_paren":stack) tokens
  16.         "right_paren" -> 
  17.             case stack of
  18.                     (s:[]) -> parseSentence True tokens
  19.                     (s:st) -> parseParens st tokens
  20.         "epsilon" -> parseSentence False []
  21.         "smiley" -> case stack of
  22.             ("left_paren":[]) -> parseSentence True tokens
  23.             _ -> parseParens stack tokens
  24.         "frowney" -> parseParens stack tokens
  25.         _   -> parseParens stack tokens
  26.  
  27. parseSentence False [] = False
  28. parseSentence True [] = True
  29.  
  30. parseSentence intable (tok:tokens) =
  31.     case tok of
  32.         "ignored" -> parseSentence True tokens
  33.         "smiley" -> parseSentence True tokens
  34.         "frowney" -> parseSentence True tokens
  35.         "epsilon" -> parseSentence True tokens
  36.         "left_paren" -> parseParens ["left_paren"] tokens
  37.         "right_paren" -> False
  38.  
  39. isBalanced = parseSentence True . tokenize
  40.  
  41. yesno True = "YES"
  42. yesno False = "NO"
  43.  
  44. out n xs = "Case #"++(show n)++": "++(show $ yesno $ isBalanced xs)
  45.  
  46. parseInput xs = 
  47.     let cases = tail $ lines xs in
  48.         unlines $ map (uncurry out) (zip [1..] cases)
  49.  
  50. main = do
  51.         -- input <- readFile "./emotinput2"
  52.         -- writeFile "./emotoutput2" $ parseInput input
  53.         print $ isBalanced "((:)))"
Success #stdin #stdout 0.01s 3588KB
comments (?)
stdin
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Standard input is empty
stdout
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True
https://ideone.com/eDMpd3
language:
Haskell (ghc 8.4.4)
created:
11 years ago
visibility:
public

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