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  1. import Data.Int
  2.  
  3. main :: IO ()
  4. main = do
  5.   let ls = [262734068,-1284266430,850241238,1854436759,925227574,1072391605,
  6.             1593098480,753973039,-1320460728,1653753372,1036510631,1372732547,
  7.             2027209822,1573664868, minBound, maxBound]
  8.   print $ (== ls) $ map searchX ls
  9.  
  10. searchX :: Int32 -> Int32
  11. searchX x
  12.   | p 0 > 0   = f minBound 0
  13.   | otherwise = f 0 maxBound
  14.   where
  15.     f :: Int32 -> Int32 -> Int32
  16.     f l r =
  17.       case p m of
  18.         0  -> m
  19.         1  -> f l m
  20.         -1 -> f (m + 1) r
  21.         _  -> 0
  22.       where
  23.         m = mid l r
  24.     p = aboutX x
  25.  
  26. aboutX :: Int32 -> Int32 -> Int32
  27. aboutX x a =
  28.   case compare a x of
  29.     EQ -> 0
  30.     GT -> 1
  31.     LT -> -1
  32.  
  33. mid :: (Integral a) => a -> a -> a
  34. mid x y
  35.   | signum x == signum y = (x + negate y) `div` 2 - negate y
  36.   | otherwise            = (x + y) `div` 2
  37.  
Success #stdin #stdout 0s 6216KB
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https://ideone.com/cE4rDX
language:
Haskell (ghc 8.4.4)
created:
10 years ago
visibility:
public

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