People have solved puzzles by hand in the past. No tool is off limit, including your brain, pen, and paper. I would say the only thing that's "cheating" would

People have solved puzzles by hand in the past. No tool is off limit, including your brain, pen, and paper. I would say the only thing that's "cheating" would be looking up solutions to "solve" the problem faster than other people, whether they be the rest of the world on the global leaderboard (which is unlikely since the people who make the leaderboard are good about not posting solutions until it's full) or some friends you're competing with on a private leaderboard. Otherwise, let your conscience be your guide. As the saying goes, when you cheat, you're only cheating yourself.