It shows you what the exit routes are, what your score will be, and you can move the gates around as long as you want, so the means of finding the maximum area are entirely within your grasp.
But you have no idea what the optimal solution is, are you 1,10,50 away from it. Would be nice to have some indicator of how close you are before you submit, though I guess that's intentional.
I believe that’s the point. I had the optimal solution for some time but was convinced there was something better. Eventually I submitted, and seeing the perfect score was more thrilling after convincing myself I was an idiot.
