Maze 2 was also the last one for me to pass. A hint to others: I realized my error after reading one of the comments here (about assuming the drains have to be “1”). After doing one round of draining, I was going back to my map and just picking the next place to start draining from, rather than the best place. What’s interesting, I guess, is that this stupid method didn’t fail any of the tests, just only on submission.