The New Sudoku Players' Forum

[ellenfinkl]

This puzzle is the "diabolical" level puzzle from the American Way 5-15-2012 magazine.
It comes with the answers, so I'm just looking for the logic I'm missing--or perhaps I made a mistake?

sudoku.PNG (15.78 KiB) Viewed 1948 times

I'm not completely familiar with the terminology I've seen posted in other posts, so please explain!
Thanks so much--this one is driving me crazy.

[daj95376]

There are several single-digit Coloring patterns that are named. In your puzzle, the (*) cells represent a Skyscraper (on its side) pattern for "1". It results in three eliminations, and cracks the puzzle. There are numerous other eliminations on "1" using other named single-digit Coloring patterns.

Code: Select all

 +--------------------------------------------------------------+
 |  8     269   1269  |  159   7     156   |  3     4     26-1  |
 |  69    3     5     |  4    *169   2     | *18    68    7     |
 |  4     7     126   |  138   168   1368  |  9     5     26-1  |
 |--------------------+--------------------+--------------------|
 |  1     246   246   |  7     3     468   |  5     68    9     |
 |  5     8     3     |  2    *16    9     |  4     7    *16    |
 |  7     469   469   |  18    5     46    |  8-1   2     3     |
 |--------------------+--------------------+--------------------|
 |  2     5     7     |  189   189   18    |  6     3     4     |
 |  3     1     8     |  6     4     7     |  2     9     5     |
 |  69    469   469   |  35    2     35    |  7     1     8     |
 +--------------------------------------------------------------+
 # 55 eliminations remain

 r25c5   Skyscraper                      <> 1    r6c7,r13c9


Explanation: If r2c7<>1, then r2c5=1, r5c5<>1, and r5c9=1. Thus, any cell that sees r2c7 and r5c9 can not be "1".

Now, you get to find the Skyscraper in rows 2 & 6 for "1".

[ellenfinkl]

Thanks! I was able to solve the puzzle with your help and I learned a new technique!