The New Sudoku Players' Forum

[mith]

Code: Select all

+-------+-------+-------+
| . . . | . . . | . . . |
| . . 9 | . . . | . 8 7 |
| . 6 . | 5 . . | 4 . . |
+-------+-------+-------+
| . . 3 | . . . | 8 7 . |
| . . . | 4 2 . | 1 . . |
| . . 2 | . . 7 | . 9 . |
+-------+-------+-------+
| . . 7 | . . 9 | . 3 8 |
| . . . | 1 5 . | . . . |
| . . . | . . . | . . . |
+-------+-------+-------+
...........9....87.6.5..4....3...87....42.1....2..7.9...7..9.38...15.............

[rjamil]

Code: Select all

 +-----------------------+-----------------------+---------------------+
 | 234578   234578  1458 | 236789  346789  23468 | 23569  1256   13569 |
 | 2345     2345    9    | 236     1346    12346 | 2356   8      7     |
 | 2378     6       18   | 5       3789    238   | 4      12     139   |
 +-----------------------+-----------------------+---------------------+
 | 1456     145     3    | 69      169     156   | 8      7      2     |
 | 79       79      568  | 4       2       3568  | 1      56     356   |
 | 1568     158     2    | 368     1368    7     | 356    9      4     |
 +-----------------------+-----------------------+---------------------+
 | 12456    1245    7    | 26      46      9     | 256    3      8     |
 | 234689   23489   468  | 1       5       23468 | 7      246    69    |
 | 2345689  234589  4568 | 23678   34678   23468 | 2569   12456  1569  |
 +-----------------------+-----------------------+---------------------+

1) Row wise Sword Fish: 5 @ r267c127
2) HS: 5 @ r4c6
3) HS: 1 @ r2c6
4) Row wise Sword Fish: 4 @ r247c125
5) Row wise Jelly Fish: 6 @ r2467c1457
6) HQ: 1456 @ r1c3689
7) HQ: 1456 @ r9c3689
8) HQ: 1456 @ r2467c1
9) NP: 46 @ r19c6
10) HQ: 1456 @ r7c12 r89c3
11) NP: 46 @ r7c5 r9c6; stte

R. Jamil

[Cenoman]

Edit: not read rjamil's solution before posting. Similar sequence of fishes, a slightly different ending sequence of basics.
Just a different presentation of the same.

Three fishes and basics, in two steps:

Code: Select all

 +----------------------------+----------------------------+--------------------------+
 |  23478-5   23478-5  1458   |  236789   346789   23468   |  2369-5  1256    13569   |
 |  2345*     2345*    9      |  236      1346     12346   |  2356*   8       7       |
 |  2378      6        18     |  5        3789     238     |  4       12      139     |
 +----------------------------+----------------------------+--------------------------+
 |  146-5     14-5     3      |  69       169      156     |  8       7       2       |
 |  79        79       568    |  4        2        3568    |  1       56      356     |
 |  1568*     158*     2      |  368      1368     7       |  356*    9       4       |
 +----------------------------+----------------------------+--------------------------+
 |  12456*    1245*    7      |  26       46       9       |  256*    3       8       |
 |  234689    23489    468    |  1        5        23468   |  7       246     69      |
 |  234689-5  23489-5  4568   |  23678    34678    23468   |  269-5   12456   1569    |
 +----------------------------+----------------------------+--------------------------+

1. Swordfish (5)r267\c127 => -5 r149c12, -5 r19c7; 2 placements & basics

Code: Select all

 +--------------------------+----------------------------+-------------------------+
 |  2378-4   2378-4  1458   |  23789-6  3789-46  23468   |  239-6  1256    13569   |
 |  2345^    2345^   9      |  236#     346^#    1       |  2356#  8       7       |
 |  2378     6       18     |  5        3789     238     |  4      12      139     |
 +--------------------------+----------------------------+-------------------------+
 |  146^#    14^     3      |  69#      169#     5       |  8      7       2       |
 |  79       79      568    |  4        2        368     |  1      56      356     |
 |  1568#    158     2      |  368#     1368#    7       |  356#   9       4       |
 +--------------------------+----------------------------+-------------------------+
 |  12456^#  1245^   7      |  26#      46^#     9       |  256#   3       8       |
 |  2389-46  2389-4  468    |  1        5        23468   |  7      246     69      |
 |  2389-46  2389-4  4568   |  2378-6   378-46   23468   |  29-6   12456   1569    |
 +--------------------------+----------------------------+-------------------------+

2a. Swordfish ^ (4)r247\c125 => -4 r19c125, -4 r8c12
2b. Jellyfish # (6)r2467\c1457 => -6 r19c4579; basics to the end
(Basics: hidden quads (1456)r1c3689 & (1456)r9c3689; naked triple (246)b8p129; singles to the end)

[mith]

Yep, this one came up in a search for puzzles with lots of quads; this is the first one I found that actually requires 2 hidden quads (when limiting to basics and basic fish). I have a ton of these that I haven't checked thoroughly, but usually one of the hidden quads available will simplify the other(s). In this one, the quads in rows are both needed. (The naked quad in box 7 - which rjamil gave as a fourth hidden quad - will be found first by solvers, but isn't necessary.)

[pjb]

Alternatively, an MSLS followed by naked quads and naked quins:

16 cell Truths: r1358 c3689
16 links: 1456r1, 1r3, 56r5, 46r8, 8c3, 238c6, 2c8, 39c9
20 eliminations

Naked quads of 1456 at r9c3689
Naked quins of 23789 at r1c12457 => stte

Phil

[denis_berthier]

One more nice one

Hidden Text: Show

***********************************************************************************************
*** SudoRules 20.1.s based on CSP-Rules 2.1.s, config = S
*** Using CLIPS 6.32-r770
***********************************************************************************************
hidden-single-in-a-row ==> r8c7 = 7
hidden-single-in-a-row ==> r4c9 = 2
hidden-single-in-a-block ==> r6c9 = 4
244 candidates, 1797 csp-links and 1797 links. Density = 6.06%
whip[1]: r7n1{c2 .} ==> r9c3 ≠ 1, r9c1 ≠ 1, r9c2 ≠ 1
whip[1]: c3n1{r3 .} ==> r1c1 ≠ 1, r1c2 ≠ 1, r2c1 ≠ 1, r2c2 ≠ 1, r3c1 ≠ 1
whip[1]: r2n1{c6 .} ==> r1c5 ≠ 1, r1c6 ≠ 1, r3c5 ≠ 1, r3c6 ≠ 1
whip[1]: r5n9{c2 .} ==> r4c2 ≠ 9, r4c1 ≠ 9
hidden-pairs-in-a-row: r5{n7 n9}{c1 c2} ==> r5c2 ≠ 8, r5c2 ≠ 5, r5c1 ≠ 8, r5c1 ≠ 6, r5c1 ≠ 5
swordfish-in-columns: n5{c3 c8 c9}{r9 r5 r1} ==> r9c7 ≠ 5, r9c2 ≠ 5, r9c1 ≠ 5, r5c6 ≠ 5, r1c7 ≠ 5, r1c2 ≠ 5, r1c1 ≠ 5
hidden-single-in-a-block ==> r4c6 = 5
hidden-single-in-a-column ==> r2c6 = 1
swordfish-in-columns: n4{c3 c6 c8}{r8 r1 r9} ==> r9c5 ≠ 4, r9c2 ≠ 4, r9c1 ≠ 4, r8c2 ≠ 4, r8c1 ≠ 4, r1c5 ≠ 4, r1c2 ≠ 4, r1c1 ≠ 4
jellyfish-in-columns: n6{c3 c9 c6 c8}{r9 r8 r5 r1} ==> r9c7 ≠ 6, r9c5 ≠ 6, r9c4 ≠ 6, r9c1 ≠ 6, r8c1 ≠ 6, r1c7 ≠ 6, r1c5 ≠ 6, r1c4 ≠ 6
naked-quads-in-a-block: b7{r8c1 r8c2 r9c1 r9c2}{n2 n3 n8 n9} ==> r9c3 ≠ 8, r8c3 ≠ 8, r7c2 ≠ 2, r7c1 ≠ 2
hidden-quads-in-a-row: r1{n1 n4 n6 n5}{c8 c3 c6 c9} ==> r1c9 ≠ 9, r1c9 ≠ 3, r1c8 ≠ 2, r1c6 ≠ 8, r1c6 ≠ 3, r1c6 ≠ 2, r1c3 ≠ 8
hidden-quads-in-a-column: c1{n1 n5 n4 n6}{r4 r6 r2 r7} ==> r6c1 ≠ 8, r2c1 ≠ 3, r2c1 ≠ 2
hidden-quads-in-a-row: r9{n1 n5 n4 n6}{c8 c9 c3 c6} ==> r9c9 ≠ 9, r9c8 ≠ 2, r9c6 ≠ 8, r9c6 ≠ 3, r9c6 ≠ 2
naked-pairs-in-a-block: b8{r7c5 r9c6}{n4 n6} ==> r8c6 ≠ 6, r8c6 ≠ 4, r7c4 ≠ 6
stte