digits =: 10&#.^:_1

pandigital =: monad define
	ds =. /:~ digits y
	ds -: 1 + i. # ds
)

solve =: monad define
	i =. _1 p: y
	result =. 0
	while. result=0 do.
		if. pandigital p: i do.
			result =. p: i
		end.
		i =. i - 1
	end.
	result
)

problem41 =: solve 7654321 NB. Takes too long to start from 987654321