dailysudoku.com

crunched · Joined: 05 Feb 2008 Posts: 168

The puzzles have gotten much harder lately. I used to be able to do *hards*, but not anymore.
On today's puzzle, I went to the online play (after 3.5 hours of being stumped). There I hit the hint button 9 times. So far so good. Then I hit the hint button again. Voila! A 7 appears on C1, R8. How a 7 here?
Puh-lease. Can anybody tell me?
All you have to do is play online, and hit the hint button 10 times and you will be where it puts a 7 that baffles me totally.

Marty R. · Posted: Tue Feb 05, 2008 6:25 am Post subject:

Hi crunched, welcome to the forum. If you have saved your grid, could you post it? There's an article on the Site Help forum about posting aligned grids if you're not familiar with the procedure.

nataraj · Posted: Tue Feb 05, 2008 6:38 am Post subject:

This is the grid just before the "hint" (r8c9=7)

ravel · Joined: 21 Apr 2006 Posts: 536

Really a bit strange, this hint r8c1=7.

From nataraj's grid you can get there with box-line for 7 in column 4 (restricted to box 2), which takes out 7 in r4c4, then boxline for 7 in row 5 (restricted to box 5), takes out 7 in r5c1. So in column 1 there is only the 7 in r8 left.
Because after the first step you already have the single r4c2=7, it seems that the program does all possible box-line steps before returning to look for singles.

crunched · Joined: 05 Feb 2008 Posts: 168

Hey thanks! Maybe my question---as to why the sudoku computer did what it did for a hint---was somewhat unanswerable; but the BIG question was answered very nicely indeed. The BIG question for me was how to solve the puzzle, and I did get the answer. Plus, I got a nice tutor on box-line reduction ideas. Thanks a bunch! Once I apprehended the ideas involved, and applied them, the dam broke and rest of the numbers plopped into place accordingly!