2nd Generation Skyscrapers

Advanced methods and approaches for solving Sudoku puzzles

2nd Generation Skyscrapers

Postby Yogi » Sat Jul 09, 2016 4:40 am

Puzz1.png
Puzz1.png (29.36 KiB) Viewed 248 times

.97.4152.5.67.24.1421..5....459....21792586436.2.1.95.96412...5713589264258.....9

Here’s a situation where identifying one skyscraper generated two others.
8 looks a likely candidate. At this point, there is no 8Skyscraper in Columns, but {8R26} eliminates 8 from r3c9 and r4c8.
Now there is {8C29} which removes 8 from r1c1. Alternatively there is also now {8C19} which removes 8 from r6c2, and leads to the same result in Boxes 1&4, which solves the puzzle.

I’m sure this is not new, but it was new and interesting to me.
Yogi
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Re: 2nd Generation Skyscrapers

Postby Leren » Sat Jul 09, 2016 6:44 am

Your first Skyscraper has 3 eliminations and solves the puzzle.

Code: Select all
*--------------------------------------------------------------*
| 38    9     7      | 368   4     1      | 5     2     6-8    |
| 5    b38    6      | 7     39    2      | 4    a389   1      |
| 4     2     1      | 368   369   5      | 378   3789  67-8   |
|--------------------+--------------------+--------------------|
| 38    4     5      | 9     367   367    | 178   17-8  2      |
| 1     7     9      | 2     5     8      | 6     4     3      |
| 6    c38    2      | 34    1     347    | 9     5    d78     |
|--------------------+--------------------+--------------------|
| 9     6     4      | 1     2     37     | 378   378   5      |
| 7     1     3      | 5     8     9      | 2     6     4      |
| 2     5     8      | 346   367   3467   | 137   137   9      |
*--------------------------------------------------------------*

(6) r2c8 = r2c2 - r6c2 = (6) r6c9 => - 6 r13c9, r4c8; stte. The important point to note is that r2c8 and r6c9 can both see 6 cells : r123c9 and r456c8.

Leren
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2nd Generation Skyscrapers

Postby Yogi » Sat Jul 16, 2016 2:30 am

Right. That will teach me to look just a little further, but I still think it's interesting and instructive to note that the eliminations derived from one skyscraper or kite can then allow new ones that weren't there before, and they may solve the puzzle if the first one you found didn't.
Yogi
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Location: New Zealand


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