Stuck!

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Stuck!

Postby Horrorshow » Wed Oct 21, 2015 9:52 am

Hi all,

Great to see there is a forum dedicated to Sudoku. I have given up on so many puzzles hopefully I will now be able to get myself to the next level. I have read a lot of tips and techniques but they start to get very confusing to me. Any way this is a puzzle I am currently stuck on. HOPEFULLY I have not messed up a long the way and that is the reason I cannot get any further. This is a puzzle from a book with puzzles easy, medium and hard. This puzzle is marked as hard.

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


If someone could help me get the next number! What techniques you have used and if you could explain how you did it?

I am sure this is basic but I sure cannot get any further

Thanks a lot all
Horrorshow
 
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Re: Stuck!

Postby JasonLion » Wed Oct 21, 2015 12:29 pm

Where in block 9 can you place an 8?
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Re: Stuck!

Postby Horrorshow » Wed Oct 21, 2015 6:10 pm

Wow. Just wow. I am an idiot sorry for wasting your time with that one!
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Re: Stuck!

Postby Marty R. » Wed Oct 21, 2015 6:20 pm

Where in block 9 can you place an 8

Jason, did you mean box 9?
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Re: Stuck!

Postby JasonLion » Wed Oct 21, 2015 7:07 pm

I call them blocks, same thing as what many people call boxes (3x3 groups of cells).

Sudopedia lists block, nonet, region and subgrid as aliases for box.
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Re: Stuck!

Postby Horrorshow » Thu Oct 22, 2015 7:43 am

Okay I have fixed that up and i now have gone a little further


Code: Select all
7     9      4    | 3    56    1     | 2     8     56
2     3      8    | 4    56    7     | 9    51    516
1     5      6    | 8    9     2      | 4    3     7 
------------------+--------------------+-------------------
6     1      79   | 527   4    95   | 8   9245   3
5     8      3    | 6       1    94  |  7    94   124
4     2      79  | 17     8     3    | 51    6    51
------------------+--------------------+-------------------
9     6     2     | 1     3    54     | 51     7    8
3     7     5     | 9      2    8     |  6    14    124
8     4     1     | 52     7     6   | 3     52     9


should i not have an Xwing in blocks 5, 6 7, 9 using the number 5? top left, bottom left, middle top and middle bottom. problem is the book says that the number 5 goes in the cell in box 5 top right. it makes no sense to me. can anyone help?

Thanks a lot
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Joined: 21 October 2015

Re: Stuck!

Postby Leren » Thu Oct 22, 2015 9:50 am

Code: Select all
*--------------------------------------------------------------*
| 7     9     4      | 3     56    1      | 2     8     56     |
| 2     3     8      | 4     56    7      | 9     15    156    |
| 1     5     6      | 8     9     2      | 4     3     7      |
|--------------------+--------------------+--------------------|
| 6     1     79     | 257   4     59     | 8    #259   3      |
| 5     8     3      | 6     1    *9      | 7     249  $24     |
| 4     2    $79     | 57    8     3      | 15    6     15     |
|--------------------+--------------------+--------------------|
| 9     6     2      | 1     3     45     |*5     7     8      |
| 3     7     5      | 9     2     8      | 6     14   #14     |
| 8     4     1      | 5     7     6      | 3     25    9      |
*--------------------------------------------------------------*

Your puzzle is already solved ! If you compare your PM with mine you'll find that there are 2 solved cells that you've missed, that I've marked with *. For example you have r5c6 as 49 but it can't be 4, because of the 4 in r4c5.

I've also marked 2 other cells with additional eliminations due to solved cells that they can see, and I've marked these with #. For example r4c8 can't be 4 because of the 4 in r4c5.

Actually there is a third solved cell. r5c6 has the only 2 in Column 9, so it must be 2. I've marked this with $.

On further reflection there is a fourth solved cell. r6c3 has the only 9 in Row 6, so it must be 9. I've also marked this with $.

Leren
Last edited by Leren on Thu Oct 22, 2015 10:06 am, edited 2 times in total.
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Re: Stuck!

Postby Horrorshow » Thu Oct 22, 2015 10:03 am

Thanks heaps for your help! I have been staring at this for far too long lol. Next time im not posting until i am absolutely certain i cannot get any further!

Really appreciate it
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