JLynn wrote:
Two steps, an X-Wing and an XY-wing:
Thanks, JLynn!
Well, I'm very proud of myself!
I managed to finish the puzzle without peeking at your hidden hints, just based on your statement above.
For some reason I have never before thought to look for X-wings in which each instance of X is in a different box. I don't know why; it had just never occurred to me.
I did have to learn the XY-wing technique. I've never done those before, so I went to a tutorial and studied it. It took me a while to work out the logic, but then I found a slightly different XY-wing from the one you proposed:
2,5 r5c1; 2,4 r4c3; 4,5 r4c5
This technique is still going to take me some practice before I'm confident using it, but it may just help me crack some of the puzzles in my "unsolved" pile.
The upper left grid of the puzzle is stupidly easy (leaving only four cells unsolved without the center grid), and the other three grids aren't much more difficult, so the fact that this grid required me to learn a new technique is rather surprising to me.