16 and stuck. Sometimes I wonder whether those who claim "no guess" didn't just make a fortuitous mistake.
Did it, no greens, one guess. Rats. 36.
Sometimes I wonder whether those who claim "no greens" did greens in their head.
. . . Of course they did. You can't do these puzzles without keeping track of the numbers.
Two questions I am wondering about:
1. How come the use of greens is widely recognized as a technique to be avoided if at all possible?
2. Can the best Sudoku players solve expert puzzles entirely in their heads without writing anything down - no guesses, no greens, no coloring, no written record of progress?
I have a difficult time with the more involved techniques...I suppose time will tell. In the meantime, when I get as far as I can "visually", I use my own little Excel worksheet to auto-list the possibles.