Looks cute, but once one sees the trick it would appear tedious to work the whole thing out. Perhaps some kids take that in itself as kind of challenge, like a jigsaw puzzle, or finding Waldo.
I wonder if the teams that got it right invented a reliable documentation system to keep things straight. It would interesting to see how the various teams used (or did not use) their scratch paper. (And then, there would be those who do it all in the head.)