Determine if a string has all unique characters: Difference between revisions
Content added Content deleted
(→{{header|Haskell}}: Added a variation (fusion) within the string-folding draft.) |
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M.empty |
M.empty |
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(zip [0 ..] xs)))) |
(zip [0 ..] xs)))) |
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-- OR, fusing filter and minimumByMay down to a single fold: |
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duplicatedCharIndices_ :: String -> Maybe (Char, [Int]) |
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duplicatedCharIndices_ xs = |
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let go k [_] mb = mb -- Unique. |
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go k xs Nothing = Just (k, xs) -- Duplicate. |
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go k xs@(x:_) (Just (c, ys@(y:_))) = |
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if x < y |
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then Just (k, xs) -- Earlier duplicate. |
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else Just (c, ys) |
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in M.foldrWithKey |
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go |
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Nothing |
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(foldl' --' |
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(\a (i, c) -> M.insert c (maybe [i] (++ [i]) (M.lookup c a)) a) |
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M.empty |
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(zip [0 ..] xs)) |
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---------------------------TEST---------------------------- |
---------------------------TEST---------------------------- |
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, intercalate ", " (show <$> ixs) |
, intercalate ", " (show <$> ixs) |
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])) |
])) |
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duplicatedCharIndices_ |
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duplicatedCharIndices |
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["", ".", "abcABC", "XYZ ZYX", "1234567890ABCDEFGHIJKLMN0PQRSTUVWXYZ"] |
["", ".", "abcABC", "XYZ ZYX", "1234567890ABCDEFGHIJKLMN0PQRSTUVWXYZ"] |
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