Mogelijke oplossing
nqueens::Int->[Int]
-------------------
nqueens n = let
list = [1..n]
permlist = perms list
in
getoklist permlist
getoklist::[[Int]]->[Int]
------------------------
getoklist [] = error "geen oplossing"
getoklist (x:xs) | listok x = x
| otherwise = getoklist xs
listok::[Int]->Bool
-------------------
listok [] = True
listok (a:as) = if (listok2 a as 1) == False then False
else listok as
listok2::Int->[Int]->Int->Bool
------------------------------
listok2 _ [] _ = True
listok2 a (b:bs) kol | a == (b+kol) = False
| a == (b-kol) = False
| otherwise = listok2 a bs (kol+1)
--Permuteer de lijst
perms :: [k] -> [[k]]
---------------------
perms [] = [[]]
perms (x:xs) = concat (map (tussen x) (perms xs)) where
tussen e [] = [[e]]
tussen e (y:ys) = (e:y:ys) : map (y:) (tussen e ys)