by 1to9only » Tue Jun 12, 2018 2:12 pm
I guess I got a lucky hit! I lost count of tweaks made, tried one a few times, it didn't work, tried something else, etc... Here are some of the things tried (in no particular order!), towards getting a puzzle with an empty middle grid:
1) Enable naked and hidden singles only (easy puzzles), the added bonus: the program runs quicker(!). I've tried creating more difficult puzzles (i.e. enabling locked candidates and naked/hidden pairs for medium puzzles) - this is 3 times slower!! - and I think the success rate is lower as well!!
2) Generate a 'normal' kazaguruma (windmill), with (eight) empty overlapping boxes (nonets) - the majority of times, the puzzle is unsolvable (lots of unique rectangles left over) - occasionally (the 1-in-100 attempts) a puzzle with an empty middle grid is made. I've tried emptying the whole middle grid, the success rate I've had with this method is: zero.
3) Other times, the middle box in the middle grid will have givens - remove them! - re-solve - [most times, the puzzle becomes unsolvable!] sometimes, I've ended up with a puzzle with an empty middle grid!! This works better with the easy puzzles mode, much less well with the medium puzzles mode. With the easy puzzles, removing the givens in the middle box of the middle grid has sometimes resulted in a medium puzzle!!
The highlighted items seem to work for me.
Last edited by
1to9only on Tue Jun 12, 2018 5:08 pm, edited 1 time in total.
