import Data.List ( delete )

fac :: (Eq t, Num t) => t -> t
fac n = f n 1
  where
    f 0 acc = acc
    f m acc = f (m - 1) (m * acc)

perms :: Eq a => [a] -> Int -> [a] -> [a]
perms [] _ acc = reverse acc
perms xs n acc
  = perms (delete x xs) (mod n m) (x : acc)
  where 
    m = fac $ length xs - 1
    y = div n m
    x = xs !! y

p24 :: [Char]
p24 = perms "0123456789" 999999 []

λ> :set +s
λ> p24
"2783915460"
(0.02 secs, 121,968 bytes)
λ> 

— Me@2024-11-18 07:22:15 PM

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2024.11.19 Tuesday (c) All rights reserved by ACHK