Down to 154 chars, need some pointers.

Hey. So I did this challenge. And I got my code down to 154 chars. Which is pretty decent I guess.

Then I had a look at the ranking. Rookie mistake. So there are people here who did it with 74chars. That's less than half of what I got. And I used permutations, nested maps, complex numbers, lambda functions galore.

I need some pointers as to how it is possible to reduce it that much. There seem to be some major tricks that I am completely missing.