Múltiplos especiales

4 Comentarios

1. Haskell

   import Data.Numbers.Primes (primeFactors) multiplosEspecialesCota :: Int -> Int -> [Int] multiplosEspecialesCota n k = [x | x <- [n,2*n..k], all ((/=1).(`mod`3)) (primeFactors x)]

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   import Data.Numbers.Primes (primeFactors)   multiplosEspecialesCota :: Int -> Int -> [Int] multiplosEspecialesCota n k =     [x | x <- [n,2*n..k], all ((/=1).(`mod`3)) (primeFactors x)]

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   1. Se puede añadir una guarda para eliminar casos como el número 7 y 19 (primos congruentes con 1 módulo 3), y que no calcule innecesariamente cuando sabemos que devolverá la lista vacía:

      Haskell

      import Data.Numbers.Primes (primeFactors, isPrime) multiplosEspecialesCota :: Int -> Int -> [Int] multiplosEspecialesCota n k | isPrime n && n `mod` 3 == 1 = [] | otherwise = [x| x <- [n,2*n..k],all ((/=1).(`mod`3)) (primeFactors x)]

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      import Data.Numbers.Primes (primeFactors, isPrime)   multiplosEspecialesCota :: Int -> Int -> [Int] multiplosEspecialesCota n k     | isPrime n && n `mod` 3 == 1 = []     | otherwise = [x| x <- [n,2*n..k],all ((/=1).(`mod`3)) (primeFactors x)]

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2. Haskell

   import Data.Numbers.Primes (primeFactors) multiplosEspecialesCota :: Int -> Int -> [Int] multiplosEspecialesCota n k = filter especial [n,n*2..k] where especial = all (\p -> mod p 3 /= 1) . primeFactors

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   import Data.Numbers.Primes (primeFactors)   multiplosEspecialesCota :: Int -> Int -> [Int] multiplosEspecialesCota n k = filter especial [n,n*2..k]     where especial = all (\p -> mod p 3 /= 1) . primeFactors

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3. Haskell

   import Data.Numbers.Primes (primeFactors) multiplosEspecialesCota :: Int -> Int -> [Int] multiplosEspecialesCota n l = foldl f [] [l,l-1..1] where f y x | multiploEspecial x n = x:y | otherwise = y multiploEspecial :: Int -> Int -> Bool multiploEspecial m n = rem m n == 0 && and [rem x 3 /= 1| x <- primeFactors m]

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   import Data.Numbers.Primes (primeFactors)   multiplosEspecialesCota :: Int -> Int -> [Int] multiplosEspecialesCota n l = foldl f [] [l,l-1..1]     where f y x | multiploEspecial x n = x:y                 | otherwise            = y   multiploEspecial :: Int -> Int -> Bool multiploEspecial m n =     rem m n == 0 && and [rem x 3 /= 1| x <- primeFactors m]

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