dailysudoku.com

ZenDad · Joined: 17 Nov 2005 Posts: 1

I?m having trouble with this puzzle. Tried all the tricks I know and I?m stuck. I could use brute force and create a branch. But is there a better way?

000 420 600
164 589 030
028 700 045

090 208 054
201 940 300
040 300 020

639 852 400
002 194 563
415 637 000

Thanks
________
home made vaporizer

Louise56 · Posted: Thu Nov 17, 2005 11:01 pm Post subject:

Hello Zendad!

Your puzzle has a {5,8} hidden pair in r5c2 and r6c1. You can eliminate the other numbers from these two spaces. Now in row 5 you have 7's only in r5c8 and r5c9. You can eliminate 7's in the middle right 3x3 box in all the other spaces but r5c8 and r5c9.

Now you have a 1 by itself in r4c7, so r4c7 = 1. In row 7 there are only two 7's and they are in r7c8 and r7c9. In row 5 there are only two 7's and they are in r5c8 and r5c9. This makes a nice X pattern and you can see that in column 9 there must be a 7 in either r5c9 or r7c9. Likewise there must be a 7 in either r5c8 or r7c8. This means you can eliminate the 7 from r2c9 and now r2c9 = 2. Hopefully the rest will fall in place, but if not, write back.