Eban numbers: Difference between revisions

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=={{header|Haskell}}==

<lang haskell>{-# LANGUAGE NumericUnderscores #-}

anyPass :: [a -> Bool] -> a -> Bool

anyPass [] _ = False

anyPass (f:fs) x = f x || anyPass fs x

isEban :: Int -> Bool

isEban n = all (anyPass [(==0), (==2), (==4), (==6)]) z

where

(b, r1) = n `quotRem` (10 ^ 9)

(m, r2) = r1 `quotRem` (10 ^ 6)

(t, r3) = r2 `quotRem` (10 ^ 3)

z = [b] <> map (\x -> if 30 <= x && x <= 66 then x `mod` 10 else x) [m, t, r3]

main = do

putStrLn $ "eban numbers up to and including 1000: " ++ r [1..1000]

putStrLn $ "eban numbers between 1000 and 4000: " ++ r [1000..4000]

putStrLn ""

putStrLn $ "eban numbers up and including 10,000: " ++ t [1..10_000]

putStrLn $ "eban numbers up and including 100,000: " ++ t [1..100_000]

putStrLn $ "eban numbers up and including 1,000,000: " ++ t [1..1_000_000]

putStrLn $ "eban numbers up and including 10,000,000: " ++ t [1..10_000_000]

where

r = (\(c, xs) -> show c <> "\n" <> show xs <> "\n") . (\xs -> (length xs, xs)) . filter isEban

t = show . length . filter isEban</lang>

{{out}}

<pre>

eban numbers up to and including 1000: 19

[2,4,6,30,32,34,36,40,42,44,46,50,52,54,56,60,62,64,66]

eban numbers between 1000 and 4000: 21

[2000,2002,2004,2006,2030,2032,2034,2036,2040,2042,2044,2046,2050,2052,2054,2056,2060,2062,2064,2066,4000]

eban numbers up and including 10,000: 79

eban numbers up and including 100,000: 399

eban numbers up and including 1,000,000: 399

eban numbers up and including 10,000,000: 1599