The New Sudoku Players' Forum

[mith]

Code: Select all

+-------+-------+-------+
| 1 . . | 4 . 6 | . . . |
| . . 2 | . . . | . . . |
| . 3 . | . 5 . | . . . |
+-------+-------+-------+
| 8 . . | 9 . . | . 6 . |
| . . . | . 7 . | 3 . . |
| . . . | 6 1 . | . 4 8 |
+-------+-------+-------+
| . . 5 | . . 9 | 2 . . |
| 9 . . | . . . | . 8 4 |
| . . . | 1 . . | . . 9 |
+-------+-------+-------+
1..4.6.....2.......3..5....8..9...6.....7.3.....61..48..5..92..9......84...1....9

(As a reminder, these are puzzles which are rated 11+ by SE, but fall to some advanced technique not implemented by SE.)

[Leren]

Code: Select all

*----------------------------------------------------------------------------------*
| 1       5789    789      | 4       2389    6        | 5789      2357-9  2357     |
|*4567    4689-57 2        |*378     89-3    18-37    | 14689-57 *13579  *13567    |
|*467     3       4689-7   |*278     5       18-27    | 14689-7  *1279   *1267     |
|--------------------------+--------------------------+----------------------------|
| 8       12457   1347     | 9       234     2345     | 157       6       257-1    |
|*2456    1469-25 1469     |*258     7       48-25    | 3        *1259   *125      |
| 2357    2579    379      | 6       1       235      | 579       4       8        |
|--------------------------+--------------------------+----------------------------|
|*3467    1468-7  5        |*378     468-3   9        | 2        *137    *1367     |
| 9       1267    1367     | 2357    236     2357     | 1567      8       4        |
| 237-46  24678   34678    | 1       23468   234578   | 567       357     9        |
*----------------------------------------------------------------------------------*

1. MSLS : 16 Truths r2357 c1489 : 16 Links; 357r2 27r3 25r5 37r7 / 46c1 8c4 19c8 16c9; 21 eliminations as marked. Followed by basics, which gets you to here.

Code: Select all

*--------------------------------------*
| 1   57  9   | 4 3  6  | 8   25-7 257 |
| 456 468 2   | 7 9  18 | 46  15   3   |
|b467 3   468 | 2 5  18 | 46  9    a17 |
|-------------+---------+--------------|
| 8   45  14  | 9 2  3  | 17  6    57  |
| 56  9   16  | 8 7  4  | 3   125  125 |
| 3   2   7   | 6 1  5  | 9   4    8   |
|-------------+---------+--------------|
|c47  148 5   | 3 48 9  | 2  d17   6   |
| 9   17  3   | 5 6  2  | 17  8    4   |
| 2   468 468 | 1 48 7  | 5   3    9   |
*--------------------------------------*

2. Skyscraper : (7) r3c9 = r3c1 - r6c1 = (7) r7c8 => - 7 r1c8; stte

Leren

[SpAce]

Code: Select all

 \69n   \257    \37     \8n   \23    \2357    \57      \19n   \14n
.----------------------.---------------------.-----------------------.
| 1      5789    789   | 4     2389   6      | 5789     23579  2357  | *2357
| 4567   456789  2^    | 378   389    1378   | 1456789  13579  13567 |
| 467    3^      46789 | 278   5^     1278   | 146789   1279   1267  |
:----------------------+---------------------+-----------------------:
| 8      12457   1347  | 9     234    2345   | 157      6      1257  | *2357
| 2456   124569  1469  | 258   7^     2458   | 3^       1259   125   |
| 2357   2579    379   | 6     1      235    | 579      4      8     | *2357
:----------------------+---------------------+-----------------------:
| 3467   14678   5^    | 378   3468   9      | 2^       137    1367  |
| 9      1267    1367  | 2357  236    2357   | 1567     8      4     | *2357
| 23467  24678   34678 | 1     23468  234578 | 567      357    9     | *2357
'----------------------'---------------------'-----------------------'

Step 1. MF (2357 R): 20x20 {2357R14689 \ 257c2 37c3 23c5 2357c6 57c7 69n1 8n4 19n8 14n9} => 21 elims (same as Leren's)
Step 2. Something trivial; stte

[SCLT]

Step 1: Colour the 20 cells in the intersection of rows 14689 and columns 1489 blue. Colour the 20 cells in the intersection of rows 2357 and columns 23567 yellow. Observe that in any valid solution grid the blue cells and yellow cells contain the same digits with the same multiplicities.

Therefore the empty blue cells must contain 2233557 and other candidates are eliminated. The empty yellow cells must contain 114446688899 and other candidates can be eliminated.

I haven't checked but these are probably the same eliminations as Leren's MSLS.

Step 2: We still need to place exactly one 7 in the blue cells. So wherever a 7 goes in c9, there is no 7 in r1c8. Stte.

[mith]

Yeah, yours is the same as Leren's. (SpAce's version, which splits rows/columns/digits into primes and non-primes, is the reason I morphed it the way I did.)