8x8 jigsaw from youtube

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8x8 jigsaw from youtube

Postby urhegyi » Sun Dec 18, 2022 7:56 pm

I found this link on Youtube.https://www.youtube.com/watch?v=Id_a3X1SeY8
Unfortunately it's in Thai language, which I not understand.
Looking the video, it looks like trial and error.
Is there someone capable to solve this with logic?
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Postby 1to9only » Sun Dec 18, 2022 10:24 pm

SE rates this as ED=7.9/1.5/1.5.
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Re:

Postby urhegyi » Mon Dec 19, 2022 9:11 am

1to9only wrote:SE rates this as ED=7.9/1.5/1.5.

Meanwhile I solved it, but it's rather extremely hard. I looked for bivalue cells with only 2 possible candidates. Sometimes one of them wasn't possible because it emptied a region, so no placement was possible for this candidate or in another case it led to a contradiction with an already known given. So this bifurcation technique is actually a way of trial and error. I wondered if anyone could solve this with logic, probably with neater nichio chains.
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Re: Re:

Postby Hajime » Mon Dec 19, 2022 12:12 pm

urhegyi wrote:
1to9only wrote:SE rates this as ED=7.9/1.5/1.5.

Meanwhile I solved it, but it's rather extremely hard. I looked for bivalue cells with only 2 possible candidates. Sometimes one of them wasn't possible because it emptied a region, so no placement was possible for this candidate or in another case it led to a contradiction with an already known given. So this bifurcation technique is actually a way of trial and error. I wondered if anyone could solve this with logic, probably with neater nichio chains.

urhegyi, your description how you solved the puzzle is the same as explained at
https://www.sudokuwiki.org/Nishio_Forcing_Chains Type 2 and type 4.
And ED=7.9 is the rating of a Nichio Forcing chain in Sudoku Explainer. So easier/neater methods may not be expected.
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Re: 8x8 jigsaw from youtube

Postby urhegyi » Mon Dec 19, 2022 2:32 pm

Actually with pencilmarks I needed 3 steps, 2 of them relatively easy to find. The third one which breaks the puzzle was a bit of luck, but after reviewing the logic it was clear an example of nishio where one of the values of a bivalue cell forces three digits in 3 cells and where another cell which sees those three cels is empty. Knowing the correct value, the rest of the puzzle solved with basics.
Now I'm curious to see if the solvepath of sudokuexplainer did it the same (or analog)way, or was completely different. All the ways led to Rome, but perheps the one a bit quicker then the other...
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Postby 1to9only » Mon Dec 19, 2022 4:21 pm

pencilmarks: Show
Code: Select all
+--------+--------------------------+-----------------------------------+
| 134567 | 23457    2347     23457  | 8        1467     13467    36     |
|        +--------+        +--------+                          +--------+
| 34567    3457   | 1      | 8      | 2        467      3467   | 56     |
|        +--------+        |        |        +-----------------+        |
| 13468  | 2348     2348   | 12346  | 5      | 126      126      7      |
|        |                 |        +--------+        +--------+        |
| 2      | 457      6      | 1457     14     | 3      | 457    | 8      |
|        +-----------------+        +--------+        |        |        |
| 135678 | 2357     237      123567 | 136    | 1256   | 35678  | 4      |
|        |        +-----------------+        +--------+        +--------+
| 134568 | 2345   | 2348     123456   7      | 4568     34568    356    |
|        +--------+                          +--------+                 |
| 345678 | 1      | 348      3456     346      4568   | 345678   2      |
+--------+        +-----------------------------------+--------+        |
| 3478     6        5        2347     34       2478     23478  | 1      |
+--------------------------------------------------------------+--------+
....8.....182.......5..72.6..3.8.......4....7....1.....2.65....1
ABBBCCCCAABDCCCEABBDCEEEABBDDEFEADDDGEFEADGGGFFFAHGGGGFFHHHHHHHF
JS

solution: Show
Code: Select all
+---+-----------+---------------+
| 7 | 3   2   5 | 8   1   4   6 |
|   +---+   +---+           +---+
| 6   4 | 1 | 8 | 2   7   3 | 5 |
|   +---+   |   |   +-------+   |
| 3 | 8   4 | 6 | 5 | 2   1   7 |
|   |       |   +---+   +---+   |
| 2 | 7   6 | 1   4 | 3 | 5 | 8 |
|   +-------+   +---+   |   |   |
| 5 | 2   7   3 | 1 | 6 | 8 | 4 |
|   |   +-------+   +---+   +---+
| 1 | 5 | 8   2   7 | 4   6   3 |
|   +---+           +---+       |
| 8 | 1 | 3   4   6   5 | 7   2 |
+---+   +---------------+---+   |
| 4   6   5   7   3   8   2 | 1 |
+---------------------------+---+
7325814664182735384652172761435852731684158274638134657246573821
ABBBCCCCAABDCCCEABBDCEEEABBDDEFEADDDGEFEADGGGFFFAHGGGGFFHHHHHHHF
JS

solution path: Show
Code: Select all
1.5, Hidden Single: R3C2: 8 in column: r3c2=8
1.9, Direct Claiming: Cells R4C7,R5C7,R6C7,R7C7: 5 of column in jigsaw: r6c6<>5, r6c8<>5, r2c8=5
1.5, Hidden Single: R7C6: 5 in column: r7c6=5
2.8, Claiming: Cells R5C5,R7C5: 6 in column and jigsaw: r6c4<>6, r7c4<>6
2.8, Claiming: Cells R1C2,R1C3,R1C4: 2 in row and jigsaw: r3c3<>2
2.8, Claiming: Cells R4C4,R4C5: 1 in row and jigsaw: r3c4<>1, r5c4<>1
2.8, Claiming: Cells R5C1,R6C1,R7C1: 8 in jigsaw and column: r8c1<>8
2.8, Claiming: Cells R4C7,R5C7,R7C7: 7 in jigsaw and column: r1c7<>7, r2c7<>7, r8c7<>7
2.8, Claiming: Cells R1C6,R2C6: 7 in jigsaw and column: r8c6<>7
2.8, Claiming: Cells R1C6,R1C7: 1 in jigsaw and row: r1c1<>1
2.8, Claiming: Cells R6C3,R6C4: 2 in jigsaw and row: r6c2<>2
7.6, Nishio Forcing Chain (w/6 nodes): R3C1.6 on ==> R5C6.6 both on & off: r3c1<>6
7.6, Nishio Forcing Chain (w/6 nodes): R5C7.6 on ==> R3C6.6 both on & off: r5c7<>6
7.6, Nishio Forcing Chain (w/6 nodes): R6C1.3 on ==> R2C7.3 both on & off: r6c1<>3
7.7, Nishio Forcing Chain (w/7 nodes): R5C1.7 on ==> R8C4.7 both on & off: r5c1<>7
7.7, Nishio Forcing Chain (w/8 nodes): R5C1.6 on ==> R3C7.6 both on & off: r5c1<>6
7.7, Nishio Forcing Chain (w/8 nodes): R5C5.6 on ==> R3C7.6 both on & off: r5c5<>6
1.5, Hidden Single: R7C5: 6 in column: r7c5=6
2.8, Claiming: Cells R6C6,R6C7,R6C8: 6 in jigsaw and row: r6c1<>6
4.2, XY-Wing: Cells R5C5,R4C5,R7C4 on value 4: r3c4<>4, r4c4<>4
2.9, Generalized Intersection: Cells R4C5,R6C2: 4 in jigsaw: r4c2<>4
7.1, Forcing Chain (w/6 nodes): R6C1.4 off: r6c1<>4
7.7, Nishio Forcing Chain (w/8 nodes): R8C4.2 on ==> R5C6.2 both on & off: r8c4<>2
3.4, Hidden Pair: Cells R8C6,R8C7: 2,8 in row: r8c6<>4, r8c7<>3,4
7.8, Nishio Forcing Chain (w/9 nodes): R1C4.7 on ==> R2C2.7 both on & off: r1c4<>7
7.6, Nishio Forcing Chain (w/6 nodes): R2C2.7 on ==> R1C3.7 both on & off: r2c2<>7
1.9, Direct Claiming: Cells R1C1,R2C1,R7C1: 7 of jigsaw in column: r8c1<>7, r8c4=7
2.8, Claiming: Cells R5C2,R5C3: 7 in jigsaw and row: r5c7<>7
6.7, Forcing X-Chain (w/6 nodes): R1C2.4 off: r1c2<>4
6.6, Turbot Fish (w/4 nodes): R2C7.4 off: r2c7<>4
3.0, Naked Pair: Cells R1C8,R2C7: 3,6 in jigsaw: r1c6<>6, r1c7<>3,6, r2c6<>6
6.6, Turbot Fish (w/4 nodes): R6C3.4 off: r6c3<>4
7.1, Forcing Chain (w/6 nodes): R1C1.4 off: r1c1<>4
7.1, Forcing Chain (w/6 nodes): R7C1.4 off: r7c1<>4
7.2, Forcing Chain (w/8 nodes): R1C4.4 off: r1c4<>4
2.8, Claiming: Cells R6C4,R7C4: 4 in column and jigsaw: r7c3<>4
7.8, Nishio Forcing Chain (w/9 nodes): R6C3.3 on ==> R1C4.3 both on & off: r6c3<>3
7.9, Nishio Forcing Chain (w/14 nodes): R7C1.3 on ==> R6C8.3 both on & off: r7c1<>3
7.3, Forcing Chain (w/10 nodes): R4C5.1 off: r4c5<>1
1.5, Hidden Single: R5C5: 1 in column: r5c5=1
1.5, Hidden Single: R4C4: 1 in column: r4c4=1
1.5, Hidden Single: R8C5: 3 in column: r8c5=3
1.0, Hidden Single: R4C5: 4 in column: r4c5=4
1.5, Hidden Single: R2C2: 4 in column: r2c2=4
1.5, Hidden Single: R8C1: 4 in column: r8c1=4
1.5, Hidden Single: R3C3: 4 in row: r3c3=4
1.5, Hidden Single: R6C1: 1 in row: r6c1=1
1.9, Direct Claiming: Cells R1C2,R1C3,R1C4: 3 of jigsaw in row: r1c1<>3, r1c8<>3, r2c7=3
1.5, Hidden Single: R6C8: 3 in column: r6c8=3
1.0, Hidden Single: R1C8: 6 in column: r1c8=6
1.5, Hidden Single: R2C1: 6 in column: r2c1=6
1.0, Hidden Single: R2C6: 7 in row: r2c6=7
2.0, Direct Hidden Pair: Cells R1C2,R5C2: 2,3 in column: r1c2<>5,7, r5c2<>5,7, r4c2=7
1.0, Hidden Single: R4C7: 5 in row: r4c7=5
1.5, Hidden Single: R6C2: 5 in column: r6c2=5
1.5, Hidden Single: R5C3: 7 in column: r5c3=7
1.5, Hidden Single: R1C4: 5 in column: r1c4=5
1.5, Hidden Single: R5C1: 5 in column: r5c1=5
1.5, Hidden Single: R3C1: 3 in column: r3c1=3
1.5, Hidden Single: R7C1: 8 in column: r7c1=8
1.0, Hidden Single: R1C1: 7 in column: r1c1=7
1.5, Hidden Single: R6C3: 8 in column: r6c3=8
1.5, Hidden Single: R1C3: 2 in column: r1c3=2
1.0, Hidden Single: R7C3: 3 in column: r7c3=3
1.0, Hidden Single: R1C2: 3 in jigsaw: r1c2=3
1.0, Hidden Single: R5C2: 2 in column: r5c2=2
1.5, Hidden Single: R6C4: 2 in column: r6c4=2
1.0, Hidden Single: R7C4: 4 in jigsaw: r7c4=4
1.0, Hidden Single: R7C7: 7 in row: r7c7=7
1.5, Hidden Single: R5C4: 3 in column: r5c4=3
1.0, Hidden Single: R3C4: 6 in column: r3c4=6
1.5, Hidden Single: R8C6: 8 in column: r8c6=8
1.0, Hidden Single: R8C7: 2 in row: r8c7=2
1.5, Hidden Single: R3C6: 2 in column: r3c6=2
1.0, Hidden Single: R3C7: 1 in row: r3c7=1
1.0, Hidden Single: R5C6: 6 in jigsaw: r5c6=6
1.0, Hidden Single: R5C7: 8 in row: r5c7=8
1.5, Hidden Single: R1C6: 1 in column: r1c6=1
1.0, Hidden Single: R6C6: 4 in column: r6c6=4
1.0, Hidden Single: R1C7: 4 in row: r1c7=4
1.0, Hidden Single: R6C7: 6 in column: r6c7=6
ED=7.9/1.5/1.5
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