The New Sudoku Players' Forum

[Red]

8** *9* *64
**6 423 8**
**4 685 *9*
485 276 931
367 914 **8
2** 358 746
57* 84* 6**
**8 562 4**
64* *3* *8*


Been doing these casually for a few weeks but this is a level 4 difficulty and I'm not sure how to go on from here. Still not up on all the strategies and lingo just yet so I may need the laymans terms to get it. Any help though is appreciated. Thanks in advance.

[ronk]

I'm not sure how to go on from here.

It's hard to give a specific answer without your candidate list. Assuming you have a candidate list, can you post something like the below to show where you're actually at?

Code: Select all

 
 *-----------------------------------------------------------*
 | 8     1235  123   | 17    9     17    | 1235  6     4     |
 | 179   159   6     | 4     2     3     | 8     157   57    |
 | 17    123   4     | 6     8     5     | 123   9     237   |
 |-------------------+-------------------+-------------------|
 | 4     8     5     | 2     7     6     | 9     3     1     |
 | 3     6     7     | 9     1     4     | 25    25    8     |
 | 2     19    19    | 3     5     8     | 7     4     6     |
 |-------------------+-------------------+-------------------|
 | 5     7     1239  | 8     4     19    | 6     12    239   |
 | 19    139   8     | 5     6     2     | 4     17    379   |
 | 6     4     129   | 17    3     179   | 125   8     2579  |
 *-----------------------------------------------------------*


[Red]

| 8 235 23 | 17 9 17 | 235 6 4 |
| 179 159 6 | 4 2 3 | 8 157 57 |
| 17 123 4 | 6 8 5 | 123 9 237 |
|-------------------+-------------------+-------------------|
| 4 8 5 | 2 7 6 | 9 3 1 |
| 3 6 7 | 9 1 4 | 25 25 8 |
| 2 19 19 | 3 5 8 | 7 4 6 |
|-------------------+-------------------+-------------------|
| 5 7 1239 | 8 4 19 | 6 12 239 |
| 19 139 8 | 5 6 2 | 4 17 379 |
| 6 4 129 | 17 3 179 | 125 8 2579 |
*-----------------------------------------------------------*

This is where I'm at at the moment....not quite sure where to go from here. A few different routes I went had me doubling up numbers in a row, box, or column which I know proves I'm going wrong somewhere or another....

[ronk]

Locked candidate - Box 7 (lower left) has a candidate in one column only.

[Ruud]

This sudoku has indeed a locked candidate.

I prefer to examine the intersection of Column 2 and Box 1, and have a long hard look at Digit 2.

This must be an option you overlooked, since you have used this technique a few times in this puzzle, Red.

Ruud.

[Red]

Ronk, how do I determine the locked candidate in box 7 that you spotted? Am I just missing it? Looks like I have the solution now though. The approach I used in the first row, box 2, 3 and box 6 of row 1, all shared the digits 235. From here I eliminated the 2 and 3 as options in column 2, box 3, leaving just the 1 as the only number to fill that spot. From here I solved the rest of the puzzle relatively easily. Ronk, how do I determine the locked candidate in box 7 that you spotted? Am I just missing it? Now, did I go about everything else correctly? I realize that going that route led me to the solution but will every puzzle follow the same basic guidelines? As I stated, I am pretty new to the puzzles but can handle levels 1-3 with ease but get a little crossed up at this level and beyond......The solution then if I'm not mistaken.....


823 197 564
956 423 817
714 685 392
485 276 931
367 914 258
291 358 746
579 841 623
138 562 479
642 739 185

[ronk]

Looks like I have the solution now though. The approach I used in the first row, box 2, 3 and box 6 of row 1, all shared the digits 235. From here I eliminated the 2 and 3 as options in column 2, box 3, leaving just the 1 as the only number to fill that spot. From here I solved the rest of the puzzle relatively easily.

First of all, what you are calling "box" is more commonly known as cell or square. Cells are commonly referred to by their row (r) and column (c) numbers, e.g., r1c2, r1c3, and r1c7 for the 235 naked triplet you identified.

Your elimination of 23 from r3c2 was a "happy accident" -- eliminations that turned out to be correct even though your logic was faulty. When a naked triple exists in a row, you can only make eliminations of those digits in other cells of that same row.

how do I determine the locked candidate in box 7 that you spotted? Am I just missing it?

I'd be willing to bet you didn't spot it because of your interpretation of "box". Sorry, I didn't say "3x3 box" to be clearer.

My 'locked candidate' hint was concerning the digit 2 in box 7, the lower left 3x3 box. Since all the candidate 2s are in the intersection of box 7 and col 3, a 2 cannot exist anywhere else in col 3.

Solving Sudoku by Angus Johnson has a good tutorial of the basic techniques. Techniques at the Sadman Sudoku site is also recommended a lot.

[Cec]

......The solution then if I'm not mistaken.....

Hi Red,
You may wish to view this thread to see the forum's recommended terminology for viewing/sending posts. SSH! another tip - don't show the solved puzzle - it's all about how puzzles are solved and those interested wanting to learn how to do it.
Good luck with your future solving.
Cec