start solving duo sudoku

For fans of Killer Sudoku, Samurai Sudoku and other variants

Re: start solving duo sudoku

Postby creint » Sun Aug 30, 2020 9:04 am

With my solver:
Only one step with one or more locked singles required.
Still easy.
creint
 
Posts: 222
Joined: 20 January 2018

Re: start solving duo sudoku

Postby urhegyi » Tue Oct 06, 2020 2:19 pm

twodoku1.gif
twodoku1.gif (18.01 KiB) Viewed 180 times
I think I finally found a more difficult variant I think it needs more advanced techniques. Can someone confirm this and pointing me in the right direction?
grid1
Code: Select all
.......4...92..7.3.3......6.1.76..5..75.......9.153.........32............3.47...

grid2
Code: Select all
...32.9............47.........683.4.......18..6..92.5.6......1.1.2..63...7.......

I think this has multiple solutions with r1c1 = 5 in 2nd grid (1sol) and with r1c1 = 8 in 2nd grid(3sol)
urhegyi
 
Posts: 96
Joined: 13 April 2020

Re: start solving duo sudoku

Postby creint » Tue Oct 06, 2020 4:39 pm

It has multiple solutions, you can use more advanced techniques but with that you cannot reach beyond the following:
Code: Select all
7    28   1    6    3    9    28   4    5
45   6    9    2    8    45   7    1    3
2458 3    24   45   7    1    28   9    6
3    1    8    7    6    2    4    5    9
6    7    5    48   9    48   1    3    2
24   9    24   1    5    3    6    8    7
9    45   7    58   1    6    3    2    48   9    7    45
1    45   6    3    2    58   9    7    48   45   6    1
28   28   3    9    4    7    5    6    1    8    3    2
               7    5    1    6    8    3    2    4    9
               2    3    9    7    4    5    1    8    6
               48   6    48   1    9    2    7    5    3
               6    9    45   2    3    7    45   1    8
               1    8    2    4    5    6    3    9    7
               45   7    3    8    1    9    6    2    45
creint
 
Posts: 222
Joined: 20 January 2018

Re: start solving duo sudoku

Postby urhegyi » Sun Nov 08, 2020 8:38 pm

39721_350819.png
39721_350819.png (18.23 KiB) Viewed 125 times
Found an overlapping duosudoku I never saw before. The first time solving it I struggled a lot, but the 2nd time it was really nice to solve because I discovered a rule.
How would I best start when solving more sudokus like these?
This must be the solution when I have not made a mistake:
grid1:
Hidden Text: Show
Code: Select all
679431285481572693532698471294753168768124539153986724847219356315867942926345817

grid2:
Hidden Text: Show
Code: Select all
815726934326984715947531682681245397539867241472193568158679423263458179794312856
urhegyi
 
Posts: 96
Joined: 13 April 2020

Re: start solving duo sudoku

Postby urhegyi » Sun Nov 08, 2020 9:09 pm

39394_290909.png
39394_290909.png (18.53 KiB) Viewed 121 times
Looking a second time the site sudoku.today had another example. So I know what to do tomorrow evening.
Was really easy now I understand the hidden constraints.
solution:
grid1:
Hidden Text: Show
Code: Select all
531289746297146853846537219428315967619728534753694128182473695964852371375961482

grid2:
Hidden Text: Show
Code: Select all
971468532465372198283159674197285346536941287824736951648523719759614823312897465
Last edited by urhegyi on Sun Nov 08, 2020 10:39 pm, edited 1 time in total.
urhegyi
 
Posts: 96
Joined: 13 April 2020

Re: start solving duo sudoku

Postby 1to9only » Sun Nov 08, 2020 9:42 pm

The solution for the first puzzle is correct.
Code: Select all
.............726.................16...8.2.5.9.5..8...4.4...9.....5.......263....7 ED=2.3/1.2/1.2
...726.................16...8.2.5.9.5..8...4.4...9.....5.......263....7.......... ED=1.5/1.2/1.2

The second puzzle is of similar difficulty level, puzzle rating:
Hidden Text: Show
Code: Select all
..........97....5..4..3.2.9..8....6..1.7.8..4....94................5...1..59...82 ED=2.0/1.2/1.2
97....5..4..3.2.9..8....6..1.7.8..4....94................5...1..59...82.......... ED=1.5/1.0/1.0
1to9only
 
Posts: 2119
Joined: 04 April 2018

Re: start solving duo sudoku

Postby urhegyi » Tue Nov 10, 2020 9:09 pm

Overlapping Sudoku (Daily Sudoku League #118).PNG
Overlapping Sudoku (Daily Sudoku League #118).PNG (11.3 KiB) Viewed 100 times
I like the overlapping sudokus like the last two one, but they are hard to find on the internet and mostly very easy to solve. I'm searching for examples with naked and or hidden subsets, and also with x-wing. Can someone explain how they are created? Finally I found another one and give it a try.
solution:
grid1:
Hidden Text: Show
Code: Select all
936841257215937846847256931768312495423579618591684372384725169652193784179468523

grid2:
Hidden Text: Show
Code: Select all
159378462472569318683124957235796184916843725847251693521937846794685231368412579
urhegyi
 
Posts: 96
Joined: 13 April 2020

Re: start solving duo sudoku

Postby 1to9only » Tue Nov 10, 2020 10:54 pm

Code: Select all
......2....5..784..4..5...1...3.........7...8.9...4...3.....1...5...3..4..946..2. ED=1.5/1.2/1.2
.5..784..4..5...1...3.....7...7...8.9...4.........1...5...3..4..946..2....8...... ED=1.2/1.0/1.0

urhegyi wrote:Can someone explain how they are created?

The process will be the same as discussed in: http://forum.enjoysudoku.com/how-to-create-a-sudoku-starting-from-a-solution-t38385.html.

- you'll need a solver for the overlapped puzzle.
- generate solution grids

- remove symmetric clues
- check solvable (unique solution)
- loop

- repeat until you have a puzzle of required difficulty
.
1to9only
 
Posts: 2119
Joined: 04 April 2018

Re: start solving duo sudoku

Postby creint » Wed Nov 11, 2020 9:40 am

If you don't care about that it must be minimal then you can rate ever time you remove a digit. It limits maximum difficulty but does not guarantee that difficulty.

In my solver within 10 seconds template input and a puzzle.
Here one with SE ~9, but not symmetric.
Code: Select all
. . . . . . . . . 
. . . . . . 9 4 . .
. 5 . . . 3 . 1 . .
. . . . . . . . . .
. . . . 8 . . . 3 .
. . . 4 . . 2 7 . .
. . . . . . . . . 2
1 . . . . 8 . 6 . .
. . 6 . . . 3 . . .
  9 . . . . . . 7 .


There are other ways for generating but this is the fastest way for small puzzles.
creint
 
Posts: 222
Joined: 20 January 2018

Re: start solving duo sudoku

Postby 1to9only » Wed Nov 11, 2020 11:02 am

urhegyi wrote:I like the overlapping sudokus like the last two one, but they are hard to find on the internet and mostly very easy to solve. I'm searching for examples with naked and or hidden subsets, and also with x-wing.

Try these:
http://forum.enjoysudoku.com/wc2018-knockout-flowers-t34870.html
http://forum.enjoysudoku.com/wc2018-kazaguruma-special-t34829.html

Depends on what you are looking for: number of overlapped sudokus (2, 3, 5 (samurai), ... 105!), size of overlapped region (8x8 in the last one you posted), usually the overlapped region is 1 nonet (3x3 block) as in samurai, but can be 2-4 nonets for gattais with 2-4 sudokus. Some time back I posted a number of gattais in the Sudoku variants section, most/all are in the easy/medium difficulty level. I collected all the ones I posted and a few more, and stored them here: https://github.com/1to9only/Gattai-Puzzles.

For more gattais: Ruud's Specialty Puzzles at: http://www.rcbroughton.co.uk/sudoku/forum/viewtopic.php?f=4&t=13
.
1to9only
 
Posts: 2119
Joined: 04 April 2018

Re: start solving duo sudoku

Postby urhegyi » Wed Nov 11, 2020 12:03 pm

creint wrote:If you don't care about that it must be minimal then you can rate ever time you remove a digit. It limits maximum difficulty but does not guarantee that difficulty.

In my solver within 10 seconds template input and a puzzle.
Here one with SE ~9, but not symmetric.
Code: Select all
. . . . . . . . . 
. . . . . . 9 4 . .
. 5 . . . 3 . 1 . .
. . . . . . . . . .
. . . . 8 . . . 3 .
. . . 4 . . 2 7 . .
. . . . . . . . . 2
1 . . . . 8 . 6 . .
. . 6 . . . 3 . . .
  9 . . . . . . 7 .

Is it really a SE9.0?
Solution:
grid1:
Hidden Text: Show
Code: Select all
491826537368751942752943816514372689627189453839465271285637194143298765976514328

grid2:
Hidden Text: Show
Code: Select all
687519423529438167143726895271894536394652718856371942432987651765143289918265374


There are other ways for generating but this is the fastest way for small puzzles.
urhegyi
 
Posts: 96
Joined: 13 April 2020

Re: start solving duo sudoku

Postby urhegyi » Wed Nov 11, 2020 7:35 pm

In all 4 examples of the 8x8 overlapping grid I found this constraints:

grid1 r1c1 = grid2 r9c9
grid1 ri+1c1 = grid2 ric9

grid1 r1c1 = grid2 r9c9
grid1 r1ci+1 = grid2 r9ci
urhegyi
 
Posts: 96
Joined: 13 April 2020

Re: start solving duo sudoku

Postby Hajime » Thu Nov 12, 2020 9:26 am

urhegyi wrote:In all 4 examples of the 8x8 overlapping grid I found this constraints: ....

Because there is an overlapping of 8 cells the outermost 2 cells (one per grid) must be equal.
But I confirm that the puzzle of creint is indeed very hard, so did you have a lucky guess or do you have extreme skills?

Here is a duo puzzle with 7x7 overlap:
duo_easy.png
duo_easy.png (5.37 KiB) Viewed 32 times

Solution is easy, only naked/hidden pairs,triples or quads needed.
In code:
Code: Select all
#2//B4/D8
....7..9......4....3....4.....................25.....6.....7.1.47.............2..
....4...........7..........5.....6.1...7.1.9..............2.......1....6..3......

And here a more difficult one. Same layout but chains are needed.
Code: Select all
#2//B4/D8
.....1..........67............4...............2.7...4..5....61.47.6......1.9...7.
.......3..4..............6..7...4.......61....6........9...7......1...5.........9

Because of the 7x7 overlap the 2 outermost pairs per row/col must be equal, but may be exchanged.

All generated with SiSeSuSo.exe
User avatar
Hajime
 
Posts: 230
Joined: 20 April 2018
Location: Netherlands

Re: start solving duo sudoku

Postby 1to9only » Thu Nov 12, 2020 12:23 pm

The first 2 8x8 overlapped sudokus solve as JSBs (Jigsaw Sudoku with Block constraints).
Code: Select all
.............726.................16...8.2.5.9.5..8...4.4...9.....5.......263....7 ED=3.0
..........97....5..4..3.2.9..8....6..1.7.8..4....94................5...1..59...82 ED=1.2

So I generated some JSBs, and some can be solved as 8x8 overlapped sudokus!

Easy:
Code: Select all
. . . . . . . . .
. . 7 . 9 . . . . .
. . . . 2 6 5 . . .
. 2 8 . . . . 9 . .
. . . . . . 6 . . .
. . . 5 . 9 . . 7 .
. 3 . . . 7 . 8 . .
. 8 . . . . . . . .
. . . . . . . . 1 .
  . . . . . . . . .

...........7.9........265...28....9.......6.....5.9..7.3...7.8..8...............1 ED=1.5/1.2/1.2
.7.9........265...28....9.......6.....5.9..7.3...7.8..8...............1.......... ED=2.0/1.2/1.2

Medium:
Code: Select all
. . . . . . . . .
. . . . 7 . 9 . . .
. 8 . . . . . 3 . .
. 7 . . . . 2 . . .
. . 5 4 6 . . . 8 .
. 6 . . . . 3 . . .
. . . . . . . 5 . .
. . . 1 . . . . 4 .
. . 4 . 5 . . . . .
  . . . . . . . . .

.............7.9...8.....3..7....2....546...8.6....3.........5....1....4..4.5.... ED=2.6/1.2/1.2
...7.9...8.....3..7....2....546...8.6....3.........5....1....4..4.5.............. ED=4.1/1.2/1.2

Hard:
Code: Select all
. . . . . . . . .
. 7 . . . . 1 . . .
. . . . 3 . . . 8 .
. 6 . . . . 9 2 . .
. . 9 . 8 5 . . . .
. 5 . . . 1 . . . .
. . . 4 . 7 . . 3 .
. 2 . . . . . . . .
. . . . . . 7 . . .
  . . . . . . . . .

..........7....1......3...8.6....92...9.85....5...1......4.7..3.2.............7.. ED=7.2/1.2/1.2
7....1......3...8.6....92...9.85....5...1......4.7..3.2.............7............ ED=6.6/1.2/1.2
1to9only
 
Posts: 2119
Joined: 04 April 2018

Re: start solving duo sudoku

Postby Hajime » Thu Nov 12, 2020 5:35 pm

1to9only wrote:The first 2 8x8 overlapped sudokus solve as JSBs (Jigsaw Sudoku with Block constraints).
Code: Select all
.............726.................16...8.2.5.9.5..8...4.4...9.....5.......263....7 ED=3.0
..........97....5..4..3.2.9..8....6..1.7.8..4....94................5...1..59...82 ED=1.2

Is this code correct?

1to9only wrote:So I generated some JSBs, and some can be solved as 8x8 overlapped sudokus!


Easy: Singles only confirmed
Medium: Naked/Hidden Pairs/Triplets and Pointing/Claiming is confirmed
Hard: Besides Basic Methods I needed an X-chain and an XY-chain (bivalue) both of length 6 (and some Skyscrapers).
User avatar
Hajime
 
Posts: 230
Joined: 20 April 2018
Location: Netherlands

PreviousNext

Return to Sudoku variants