The New Sudoku Players' Forum

[kiyoshige]

I think there is an ALS in this puzzle, but I can't find it.

Code: Select all

 *-----------------------------------------------------------------------------*
 |                         | 9       4       3       |                         |
 |                 6       |                         |                 8       |
 |                 5       |                         |         1               |
 |-------------------------+-------------------------+-------------------------|
 | 9       8               |                         |                         |
 |                         | 6       1       2       |                         |
 |                         |                         |         4       7       |
 |-------------------------+-------------------------+-------------------------|
 |         1               |                         | 9                       |
 | 3                       |                         | 2                       |
 |                         | 5       7       8       |                         |
 *-----------------------------------------------------------------------------*


Then I have it down to....

Code: Select all

 *-----------------------------------------------------------------------------*
 | 18      27      18      | 9       4       3       | 567     256     26      |
 | 247     39      6       | 127     25      15      | 347     239     8       |
 | 247     39      5       | 278     68      67      | 347     1       2349    |
 |-------------------------+-------------------------+-------------------------|
 | 9       8       13      | 47      35      47      | 1356    2356    1236    |
 | 57      457     347     | 6       1       2       | 8       359     39      |
 | 156     56      2       | 38      89      59      | 135     4       7       |
 |-------------------------+-------------------------+-------------------------|
 | 5678    1      *478     | 23      23      46      | 9      *78      456     |
 | 3       4567   *478     | 14      69      19      | 2      *78      456     |
 | 26      246     9       | 5       7       8       | 1346    36      1346    |
 *-----------------------------------------------------------------------------*


So, I can then say that r5c3, r8c2 and r9c2 cannot be 4? Solves the puzzle, thanks!

[tarek]

I would probably go for unique rectangles before jumping to ALS...

Code: Select all

*--------------------------------------------------------*
| 18    27    18   | 9     4     3    | 567   256   26   |
| 247   39    6    | 127   25    15   | 347   239   8    |
| 247   39    5    | 278   68    67   | 347   1     2349 |
|------------------+------------------+------------------|
| 9     8     13   | 47    35    47   | 1356  2356  1236 |
| 57    457   347  | 6     1     2    | 8     359   39   |
| 156   56    2    | 38    89    59   | 135   4     7    |
|------------------+------------------+------------------|
| 5678  1    *478  | 23    23    46   | 9    *78    456  |
| 3     4567 *478  | 14    69    19   | 2    *78    456  |
| 26    246   9    | 5     7     8    | 1346  36    1346 |
*--------------------------------------------------------*

tarek

[udosuk]

So, I can then say that r5c3, r5c2, r8c2 and r9c2 cannot be 4? Solves the puzzle, thanks!

r5c3, r89c2 cannot be 4 from the UR... But r5c2 is forced to be 4...

[tarek]

So, I can then say that r5c3, r5c2, r8c2 and r9c2 cannot be 4?

r7c3 or r8c3 must have a 4 if we have a unique solution.....

therefore all other 4s in column 3 & Box 7 can be eliminated.......& as udosuk pointed out, following that r5c2 is a 4 (hidden single)

tarek

[EmmaG1959]

Where did the original come from? I've at last progressed to the stage where I can be confident of finishing Times Fiendish puzzles, but only because I seem to be able to do that without use of 'advanced techniques'. What is an ALS?

I can't get quite as far as the original poster, but shan't bother posting my stuck state as I'm going on holiday in half an hour!

I suspect my mental block over X-wings (I've read and read it but never been able to use it) never mind Y-wings is going to let me down....

[EmmaG1959]

Sorry, ALS is an almost locked set 0 I couldn't see the header! But I'm none the wiser....

[tarek]

You wouldn't need any Unique rectangles or ALS to solve The Times puzzles....... They are good techniques to know but generally you wouldn't need to use them until the puzzle level surpasses the Superior level....

tarek