El problema del número perdido

8 Comentarios

1. Haskell

   numeroPerdido :: [Int] -> Maybe Int numeroPerdido t@(x:y:xs) | abs (y - x) == 1 = cabezaSegura [a | (a,b) <- zip [x,y..] t, a /= b] | otherwise = Just (x + head xs - y) cabezaSegura :: [Int] -> Maybe Int cabezaSegura [] = Nothing cabezaSegura xs = Just (head xs)

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   numeroPerdido :: [Int] -> Maybe Int numeroPerdido t@(x:y:xs)   | abs (y - x) == 1 = cabezaSegura [a | (a,b) <- zip [x,y..] t, a /= b]   | otherwise        = Just (x + head xs - y) cabezaSegura :: [Int] -> Maybe Int cabezaSegura [] = Nothing cabezaSegura xs = Just (head xs)

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2. Haskell

   numeroPerdido :: [Int] -> Maybe Int numeroPerdido (x:y:z:xs) | (x + z) `div` 2 /= y = Just (x + (z - y)) | null zs = Nothing | otherwise = Just (head zs ) where zs = [k | (k,q) <- zip [x,y..] (x:y:z:xs), k /= q]

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   numeroPerdido :: [Int] -> Maybe Int numeroPerdido (x:y:z:xs)   | (x + z) `div` 2 /= y = Just (x + (z - y))   | null zs              = Nothing   | otherwise            = Just (head zs )   where zs = [k | (k,q) <- zip [x,y..] (x:y:z:xs), k /= q]

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3. Haskell

   import Data.List (tails) import Data.Maybe (listToMaybe) numeroPerdido :: [Int] -> Maybe Int numeroPerdido xs = listToMaybe [(a+b) `div` 2 | (a:b:_) <- tails xs, abs(a-b) /= 1]

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   import Data.List (tails) import Data.Maybe (listToMaybe)   numeroPerdido :: [Int] -> Maybe Int numeroPerdido xs = listToMaybe [(a+b) `div` 2 | (a:b:_) <- tails xs, abs(a-b) /= 1]

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4. Haskell

   numeroPerdido :: [Int] -> Maybe Int numeroPerdido [] = Nothing numeroPerdido [x] = Nothing numeroPerdido (x:y:xs) | y == x+1 || y == x-1 = numeroPerdido (y:xs) | y /= x+1 && head xs > y = Just (x+1) | y /= x-1 && head xs < y = Just (x-1)

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   numeroPerdido :: [Int] -> Maybe Int numeroPerdido []  = Nothing numeroPerdido [x] = Nothing numeroPerdido (x:y:xs)   | y == x+1 || y == x-1    = numeroPerdido (y:xs)   | y /= x+1 && head xs > y = Just (x+1)   | y /= x-1 && head xs < y = Just (x-1)

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5. Haskell

   numeroPerdido :: [Int] -> Maybe Int numeroPerdido (x:y:xs) | abs (y - x) == 1 = numeroPerdido (y:xs) | otherwise = Just (div (x+y) 2) numeroPerdido _ = Nothing

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   numeroPerdido :: [Int] -> Maybe Int numeroPerdido (x:y:xs)   | abs (y - x) == 1 = numeroPerdido (y:xs)   | otherwise        = Just (div (x+y) 2) numeroPerdido _      = Nothing

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6. Haskell

   numeroPerdido :: [Int] -> Maybe Int numeroPerdido (x:xs) | head xs - x > 0 = aux (x:xs) | otherwise = aux' (x:xs) aux :: [Int] -> Maybe Int aux (x:xs) | null xs || length xs == 1 = Nothing | x+1 /= head xs = Just (x+1) | otherwise = numeroPerdido xs aux' :: [Int] -> Maybe Int aux' (x:xs) | null xs || length xs == 1 = Nothing | x-1 /= head xs = Just (x-1) | otherwise = numeroPerdido xs

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   numeroPerdido :: [Int] -> Maybe Int numeroPerdido (x:xs)   | head xs - x > 0 = aux (x:xs)   | otherwise       = aux' (x:xs)   aux :: [Int] -> Maybe Int aux (x:xs)   | null xs || length xs == 1 = Nothing   | x+1 /= head xs            = Just (x+1)   | otherwise                 = numeroPerdido xs   aux' :: [Int] -> Maybe Int aux' (x:xs)   | null xs || length xs == 1 = Nothing   | x-1 /= head xs            = Just (x-1)   | otherwise                 = numeroPerdido xs

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7. Haskell

   import Data.List (sort) numeroPerdido :: [Int] -> Maybe Int numeroPerdido xs = numeroPerdidoAux (sort xs) numeroPerdidoAux :: [Int] -> Maybe Int numeroPerdidoAux [] = Nothing numeroPerdidoAux [x] = Nothing numeroPerdidoAux (x:y:xs) | x+1 == y = numeroPerdidoAux (y:xs) | otherwise = Just (x+1)

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   import Data.List (sort)   numeroPerdido :: [Int] -> Maybe Int numeroPerdido xs = numeroPerdidoAux (sort xs) numeroPerdidoAux :: [Int] -> Maybe Int numeroPerdidoAux []  = Nothing numeroPerdidoAux [x] = Nothing numeroPerdidoAux (x:y:xs)   | x+1 == y  = numeroPerdidoAux (y:xs)   | otherwise = Just (x+1)

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8. Solución en Maxima:
   numeroPerdido (xs) := if (length(xs)<2)
   then Nothing else g(xs)$
   g(xs):=if (abs(second(xs)-first(xs))=1) then
   numeroPerdido (rest(xs)) else
   (Just ((first(xs)+second(xs))/ 2)) $

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