community-level/732

[giscus[bot]]

community-level/732

Queens game by Sami

https://queensgame.vercel.app/community-level/732

[star-droid-prog]

I'm sure there is logic but first time round was a cludge of logic and trial and error.

[star-droid-prog]

Scratch that. I got through convoluted logic. This is a beautifully made puzzle.

[Centurions32]

I got to the point where I could place 7 queens, but that's when the wheels fell off the bus for me. I keep thinking there is a 3-color X-Wing in D, O, and F, but I can't get it to work. I'll leave it and come back to it tonight.

[VictorBandoiu]

For me I noticed that a x-Wing with D, E , G, O Row 11/12 and Columns 11, 14 was almost possible... except the 4 Gs ( R4-6, C4-5) in the top-left.

But if there was a queen in 4G cells you'd force O/C queen and lead to conflict on J/D

So then if you x the 4Gs and x-Wing these it becomes solvable.

[Centurions32]

Thanks Victor. There is no way I would have gotten the 4G's in the top-left on my own.

[MikeSchoenhals]

excellent puzzle! very straightforward - 100% logical and no lookahead or guessing required!

[VictorBandoiu]

I see calculations when considering forceful moves as not guessing. Like in chess you can give a forced checkmate (which is a puzzle) with bishop and knight, but you have to rely on both strategy and tactics. Best players of chess calculate a checkmate, but they don't do like computers to guess/look at all moves, they look for forceful moves.

[MikeSchoenhals]

the trick is that there is a 4-way Z-wing (i'm not calling it an x-wing since it's not a true x-wing - 4 non-overlapping rows/columns covering exactly 4 colors) for C,G,J,K on rows 7,9 and columns 7,9 (after enough cells have been eliminated). C,G,J,K have to be in those rows and columns. (feel free to put a spoiler around this - I don't know how).

[VictorBandoiu]

Not sure how you got there after placing the 7 queens:

Details

But you have to do lots of calculations from this point imo to make that work

For me D, E , G, O Row 11/12 and Columns 11, 14 was almost possible except the 4 G cells in top-left.
And you can do area exclusion with H/G on Y axis and with F/D/G on X axis... it fails and an x-wing can be applied

[VictorBandoiu]

Silly me it does work nicely 😅 Good find Mike!

[MikeSchoenhals]

after that Z-wing, the rest is very straightforward. you can pin G down to column 14. You then eliminate O and D in that column, which gives allows you to identify D in R-5, C-11. You can also then pin down O and H. it's straightforward from there.

[GuillermoAbadLopez]

Wow, i was stuck exactly at this point.

Amazing finding Mike, that X-wing on the middle (7/9s), with all the intersections X'ed from before, forces all 4 colors inside, basically solving it 🙌