After basics :
- Code: Select all
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| 1234   23456  23456  | 49     45     14569  | 7      4589   1489   |
| 14     456    456    | 7      458    145689 | 1459   3      2      |
| 8      7      9      | 234    2345   12345  | 145    6      14     |
|--------------------------------------------------------------------|
| 234*   1      8      | 2349*  7      23459  | 6      2459   349    |
| 5      9      234*   | 1      6      234*   | 8      247    347    |
| 6      234*   7      | 8      2345*  23459  | 123459 2459   1349   |
|--------------------------------------------------------------------|
| 2349   2348   234*   | 6      2348*  7      | 2349   1      5      |
| 7      23468* 1      | 5      9      2348*  | 234    248    3468   |
| 2349*  234568 23456  | 234*   1      2348   | 2349   24789  346789 |
|--------------------------------------------------------------------|
Tridagon  {2,3,4}  in cells (*)
with  7 guardians :  9r4c4,5r6c5,6r8c2,8r8c2,9r9c1,8r7c5,8r8c6
As for the previous puzzle (#1418) I found that W + Trid-OR7W > gW + Trid-OR7gW:
W9 + ORk-W9  but  gW6 + ORk-W6.
… and also  S2-W6 + ORk-S2-W6.
But S2-chains are particularly interesting here to reduce the number of steps:
g-whip[7]: r1n8{c9 c8}- b3n9{r1c8 r2c7}- c7n1{r2 r6}- c7n5{r6 r3}- c7n4{r3 r789}- r8c8{n4 n2}- c7n2{r8 .} => -1r1c9
Naked quads: 4589r1c4589 =>  -4r1c1 -4r1c2 -5r1c2 -4r1c3 -5r1c3 -4r1c6 -5r1c6 -9r1c6
Box/Line: 4b1r2 =>  -4r2c5 -4r2c6 -4r2c7
Box/Line: 5b1r2 =>  -5r2c5 -5r2c6 -5r2c7
Single(s): 8r2c5, 8r7c2
5 guardians remaining :  9r4c4,5r6c5,6r8c2,9r9c1,8r8c6
Trid-OR5-S2-whip[9]: r2n9{c6 c7}- r7n9{c7 c1}- r9{c1n9 HP:c89n79}- c9n6{r9 r8}- b9n8{r8c9 r8c8}- OR5{{n9r4c4  n6r8c2 n9r9c1 n8r8c6 | n5r6c5}}- r1n5{c5 c8}- r4n5{c8 .} => -9r1c4
Single(s): 4r1c4, 5r1c5, 5r3c7, 4r3c9, 1r3c6, 6r1c6, 9r2c6, 1r2c7, 4r2c1, 1r1c1, 1r6c9, 9r4c4, 3r4c9, 2r4c1, 7r5c9, 7r9c8
Box/Line: 3c1b7 =>  -3r7c3 -3r8c2 -3r9c2 -3r9c3
Hidden pairs: 56c3r29 =>  -2r9c3 -4r9c3
whip[2]: c3n4{r5 r7}- c5n4{r7 .} => -4r5c6
whip[2]: c3n4{r5 r7}- c5n4{r7 .} => -4r6c2
STTE