I got the correct answer immediately because I've seen a similar problem before in HN, although with a Tetris lamp instead. Link: http://jackm.co.uk/the-simple

I got the correct answer immediately because I've seen a similar problem before in HN, although with a Tetris lamp instead. Link: http://jackm.co.uk/the-simple-proof-of-the-tetris-lamp/ http://jackm.co.uk/the-simple-proof-of-the-tetris-lamp/ Discussion: https://news.ycombinator.com/item?id=8870479 https://news.ycombinator.com/item?id=8870479