dailysudoku.com

aplanells · Joined: 22 Jun 2006 Posts: 1

i need help with todays puzzle

I have
65-3-71-9
7-46913-5
39125--76
5-31769-2
-7--3--61
----29537
---76-2-4
------7-8
4-79-2653

The hint is in r9c2 a 1 but i cant get there
thanks

Marty R. · Posted: Thu Jun 22, 2006 5:14 pm Post subject:

I do these things strictly with pencil and paper, so I'm not looking at what you are. But I had the same numbers filled in as you, except I hadn't yet solved r5c5 for "3."

There is an X-wing on "2" in cols 13 and rows 58. This eliminates the "2" from r8c2, which opens up a Type 4 rectangle on "29" in boxes 47. That solves the "19" in box 9. r2c2 can then be solved for "2." Standard elimination techniques solve a bunch of cells, including r9c5 for "8", which takes care of the hinted-at r9c2.

After proceeding with basic stuff from there, a Type 1 rectangle on "45" opens up in boxes 5 and 8. After that, basic stuff completes the puzzle.

Steve R · Posted: Thu Jun 22, 2006 7:02 pm Post subject:

Most likely the hint used the X-wing for 8 based on rows 2 and 4. This eliminates 8 from r9c2 and the rest of the puzzle is straightforward.

Steve

Blas · Joined: 19 Jul 2005 Posts: 8

I read the posts with interest cos I am still struggling and grateful for any help, please!

1 - How is the 3 in r5c5 deduced?
2 - Everytime i think I have grasped X-wings, I realize I haven't. I thought the number had to be unique for the columns? But I have an alternative "2" in r1c3.
3 - Just re-looked at the bit about the x-wing on 8s on r24c28 and see that x-wing but not the one on "2"s.

---blas

David Bryant · Joined: 29 Jul 2005 Posts: 559 Location: Denver, Colorado

Charles · Posted: Sat Jun 24, 2006 5:55 am Post subject: June 22, 06 Very hard

I, too, cannot see the three at R5C5 in the original post. I looked at this one a long time and overlooked the "8" X-Wing because I kept being drawn to the multiple Unique Rectangles in this puzzle. Has anyone devoted some thought to the "overlapping of URs". i.e could all of the possible "necessary choices" brought about by the URs somehow lead to contradictions which could possibly lead to a logical single choice or chain of choices for all of the URs. Naturally, this is leading to some serious investigation. A disclaimer - I have not read about Unique Rectangles beyond the description. Enjoyed the discussion. Charles

Chuck B · Joined: 24 Jun 2006 Posts: 24

Steve's X-wing solution is elegant.

A slightly longer solution illustrates simple coloring.

From this point:

Chuck B · Joined: 24 Jun 2006 Posts: 24

TKiel · Joined: 22 Feb 2006 Posts: 292 Location: Kalamazoo, MI

Chuck B,

There has been some discussion about making individual numbers contained in a grid different colors but nobody could figure out how to do it. Congrats on figuring it out, it sure makes following some explanations much simpler. How do you do it, if you wouldn't mind sharing?

Marty R. · Posted: Sun Jun 25, 2006 4:10 pm Post subject:

Chuck B · Joined: 24 Jun 2006 Posts: 24

Thanks, Tracy!,

When composing the message, I just selected the digit I wanted to color and applied the 'Font colour' option above the edit box. Unfortunately, you can't do that inside of a code block, and I couldn't figure out how to invoke a fixed font outside of a code block, so it was a challenge to achieve grid spacing that wasn't totally unreasonable.

By way of example, this red 8 and green 4 are done like this:

TKiel · Joined: 22 Feb 2006 Posts: 292 Location: Kalamazoo, MI

Marty R.,

Can you get it to do that inside the grid? I tried in my reply to Maggie Rose about 'x-wings, xy-wings' (which I noticed you beat me to, darn forum posting delay) but wasn't able to accomplish it.

TKiel · Joined: 22 Feb 2006 Posts: 292 Location: Kalamazoo, MI

Chuck B,

So the post with the colored numbers was not really inside a copy & paste grid, it was all stuff that was entered manually?

Chuck B · Joined: 24 Jun 2006 Posts: 24

TKiel · Joined: 22 Feb 2006 Posts: 292 Location: Kalamazoo, MI

Chuck B · Joined: 24 Jun 2006 Posts: 24