dailysudoku.com

keith · Posted: Wed Mar 24, 2010 11:50 pm Post subject: March 21 H

I refuse to be intimidated!

I've been staring at this all week:

Marty R. · Posted: Thu Mar 25, 2010 12:33 am Post subject:

I played it online with PMs and it wasn't that easy until I found the subset that broke it open.

nataraj · Posted: Thu Mar 25, 2010 7:41 am Post subject:

Not to "help" but in order to understand why this puzzle is so hard (pencilmarks or not). This is the grid after an initial sweep of floors and towers and then working "down" from the houses with 6 solved cells, then those with 5, then four....

Usually, for a hard or even "very hard" I never need to look at those houses with fewer than 4 solved cells. And here ....

half the grid is still empty ... ok ok I overlooked column one Smile

Amazing.

nataraj · Posted: Thu Mar 25, 2010 8:45 am Post subject:

I cannot imagine how anyone would solve puzzles like this one without PMs.
Awesome, Keith !

Spoilers ahead, this is how I did it:

A single 8 in row 9 (not very helpful)

Box / line interaction: in row 3, the "3"s must be in r3c46.
With 3 gone from r1c4, there is now a naked quad 1245 in column 4, which sets r7c4=7.

Smooth sailing from there

Marty R. · Posted: Thu Mar 25, 2010 3:42 pm Post subject:

Doing it with PMs, I was getting nowhere until Nataraj's step 3.