Stuck on Wash Post Sept 15 puzzle

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Stuck on Wash Post Sept 15 puzzle

Postby Andrea914 » Fri Sep 16, 2005 12:33 am

I'm really, really stuck on the "medium level" sudoku puzzle in today's Washington Post (page c13). What I have is this, including both the numbers filled in by the paper and the very few numbers that I was able to solve for on my own:


5,6,3, *,9,8, *,*,4
7,2,*, *,3,*, *,*,*
*,1,8, *,6,*, *,*,5

*,*,*, *,*,5, 7,3,*
*,7,1, *,*,*, 5,*,*
*,8,5, 6,7,*, *,*,*

1,*,*, *,5,*, 6,*,*
*,*,*, *,1,*, *,9,2
8,*,*, 9,2,*, *,5,*


In the top row, I can see that the only three missing numbers are 1,2, and 7; the numbers 1 and 2 could go in any of these three columns in the top row but the number 7 could only go in either the top 4th column or the top 8th column.

In the top right box, the number 7 can only go in the 8th column of the top row or in the 8th column of the 3rd row.

I keep thinking, "there's got to be a clue in this..." but I don't see how it helps me.

In the center box, the number 4 and 8 belongs in the middle column though it's not clear which number belongs where. However, because I know there are only two places that the numbers 4 and 8 can possibly go in the middle square I was able to eliminate 4 and 8 from all the other cells in the middle square.

What am I missing? Any suggestions/tips?

Thanks,

Andrea
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Joined: 15 September 2005

re: The Washington Post - 2005.Sep.15

Postby Pat » Fri Sep 16, 2005 7:33 am

.

Andrea914 wrote:I'm really, really stuck on the "medium level" sudoku puzzle in today's Washington Post.

What I have is this, including both the numbers filled in by the paper and the very few numbers that I was able to solve for on my own:

Code: Select all
 5 6 3 | . 9 8 | . . 4
 7 2 . | . 3 . | . . .
 . 1 8 | . 6 . | . . 5
-------+-------+------
 . . . | . . 5 | 7 3 .
 . 7 1 | . . . | 5 . .
 . 8 5 | 6 7 . | . . .
-------+-------+------
 1 . . | . 5 . | 6 . .
 . . . | . 1 . | . 9 2
 8 . . | 9 2 . | . 5 .


What am I missing? Any suggestions/tips?


how about starting with some easy things?

place the 5 in row 2

place the 2 in row 7, then place the 9 in row 7, then place the 5,3,4 in column 2

.
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Pat
 
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Joined: 18 July 2005

Follow up: still stuck ...

Postby Andrea914 » Mon Sep 19, 2005 12:51 am

Thanks for tip ... that brought me a few more steps to:


5,6,3 | *,9,8 | *,*,4
7,2,* | 5,3,* | *,*,*
*,1,8 | *,6,* | *,*,5
________________
*,4,* | *,8,5 | 7,3,*
*,7,1 | *,4,* | 5,*,*
*,8,5 | 6,7,* | *,*,*
________________
1,9,2 | *,5,* | 6,*,*
*,5,* | *,1,* | *,9,2
8,3,* | 9,2,* | *,5,*

And here I get stuck again ... and to think I did so well in math classes way back in high school. (Okay, this isn't math per se, but it uses logic and so does math so you would think skills in one would carry over to the other. Maybe I just need more experience with these puzzles. Or maybe just more patience.)
Andrea914
 
Posts: 3
Joined: 15 September 2005

Stuck on Wash Post Sept 15 puzzle

Postby easysurf » Mon Sep 19, 2005 3:17 am

The 9-15-05 Washington Post Su Doku can be solved without the need for pencil marks.

Visit:
http://www.easysurf.cc/su2doku.htm

to see how.
easysurf
 
Posts: 12
Joined: 14 June 2005

Re: Follow up: still stuck ...

Postby Pat » Mon Sep 19, 2005 7:39 am

.

Andrea914 wrote:Thanks for tip ... that brought me a few more steps to:
Code: Select all
 5 6 3 | . 9 8 | . . 4
 7 2 . | 5 3 . | . . .
 . 1 8 | . 6 . | . . 5
-------+-------+------
 . 4 . | . 8 5 | 7 3 .
 . 7 1 | . 4 . | 5 . .
 . 8 5 | 6 7 . | . . .
-------+-------+------
 1 9 2 | . 5 . | 6 . .
 . 5 . | . 1 . | . 9 2
 8 3 . | 9 2 . | . 5 .


And here I get stuck again ...


Maybe I just need more experience with these puzzles.
Or maybe just more patience.



yes, just more patience.

how about column 9: the 3

how about row 3: the 3, then the 9!


.
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Joined: 18 July 2005

Thanks!

Postby Andrea914 » Mon Sep 19, 2005 11:46 pm

Thanks, Pat, for giving suggestions -- twice! This time I was determined to try to avoid asking for help for a third time with the same puzzle so I plugged away at it (and put it aside when I was feeling stymized and came back to it) and finally solved the full puzzle.

I think where I went wrong before was that I sometimes forgot to check row AND column AND box in order to eliminate possibilities for a given cell, particularly after I had filled in some of the cells which meant I could erase some of the pencil marks. Your tip for trying to solve for one specific number in a specific row/column at a time was also helpful -- that helped me see in a few places that I had to have a given number x in one of two adjacent cells which sometimes meant I could eliminate that number in the pencil marks from the other cells in the same box.

Thanks!
Andrea914
 
Posts: 3
Joined: 15 September 2005


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