The Shogun Sudoku

For fans of Killer Sudoku, Samurai Sudoku and other variants

The Shogun Sudoku

Postby tarek » Sat Jan 21, 2006 2:44 pm

I was reading the Times today when I stumbled into this centipede-like Shogun Sudoku.

I'll analyse it to check if info from the portion on the right (head) is needed to solve the the portion on the left (tail).

If not, then it would be just a group of RONIN Samurai Sudokus disguised as a shogun:D

Can't wait to see the Emperor.
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Postby tarek » Sat Jan 21, 2006 8:04 pm

Left section:

I divided the shogun into 3 samurai sudokus for analysis (other subunit reconstruction is possible (e.g. cross)), I fed the first (Left side) to the solver:

no 9x9 grid was self-sufficient, so if a 9x9 grid was detached it will have multiple solutions (Pass):D

As a samurai, a unique solution was not possible with no further clues (Pass)

A unique solution was possible in 3 9x9 grids when solved as a Samurai (Top left, Bottom Left & centre) (Fail)

The best design would cause multiple solutions in any samallest subunit (9x9 grid in this case) if ANY other smallest subunit was detached. In this case 6 grids were not necessary to prove that that 3 of the remaining grids had a unique solution.

I'll continue with the middle section..........
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Postby Crazy Girl » Mon Jan 23, 2006 12:32 am

What's your/anyone's solving time for the shotgun sudoku, and does it involve anything more difficult than a naked/hidden pair:)
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Postby tarek » Mon Jan 23, 2006 12:40 am

It looked terrifying, so I decided to let my solver analize it.

It doesn't seem that it needs anything special apart from some spare time. If you try hard in one section, you will discover an x-wing, but it really doesn't need that if you introduced more clues from another one
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Postby tarek » Mon Jan 23, 2006 1:02 am

I just put the middle section,,

This one on its own seems to be valid on all aspects, however when combined with the left section I mentioned above, it solves more smaller subunits......

I will not analize more..... Too long.....

It is a good effort especially because it has an 180 symmetry, but it could have been better.

I also liked the bit about "The biggest Sudoku puzzle ever published by a newspaper".........

I thought that the 3-D sudoku had potentially 27 grids (but only 9 slices were displayed)

As I said.... Looking forward to meet the Emperor
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Postby Lindy » Mon Jan 23, 2006 2:57 am

I meet the Emperor (59 grids) and the Emperor's little brothers (14 grids, 17 grids) every two months. Very pleasant to spend some time with and they rarely give me any bother. However, this shogun turned into the runt from hell. 3 hours down and not that much to show for it. Then, when my back was turned, the neighbour's cat came in and played with it. Three hours work scrunched and torn. Oh well, maybe there'll be another one next week.

Anyhow, to get to the point, it seemed to me that the runt needed solving techniques I'm not used to. I have a couple of spare "Emperors" and "Little Brothers". Would anyone like them and be able to make a comparison against this shogun?
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Postby TN_Mike » Wed Jan 25, 2006 1:46 am

Hi all. That's one of our puzzles; I'm interested to see the feedback.

:)@ the "ronin" comment. We did test the beastie to avoid single-grid and samurai solutions, but didn't do tests for 3-grids etc. This one was done in a bit of a rush; in future we may start doing these checks.

I think we'll probably be changing the 180-degree symmetry to something more aesthetically pleasing in future.

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Our "chief of testing" spent much, much longer on it than the Times guideline. Top Notch doesn't publish suggested times, and I'm not quite certain how the Times derived the figure. Tarek is quite correct, the puzzle doesn't need x-wings or greater, but to get to a solution needs heavy use of the techniques for merged sudoku, eg "Rule of left-overs" (as I've heard it called.)

Runt indeed!:)
As I mentioned above, the "runt" can be solved without the use of x-wings or greater. This is by design, because we feel that the essence of solving merged sudoku should be more in the relationships between grids.

The Times won't be publishing one next week, or for the foreseeable future (it does take up a lot of space) but we do have two available at [ broken link ], and more are on the way. And while we're not doing gattai-59s yet, we do have something a little bigger than the Shogun. We're calling this, rather inevitably, the Sumo. We also have some two-grid merged sudokus - I recommend these (the true runts of gattai sudoku!) for picking up the techniques of merged grids.
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Postby nickmoss » Tue Jan 31, 2006 11:13 am

I took the Times pull out with me on holiday, and after getting through the killers without too much difficulty, I started on the Shogun. From what looked like it was going to be straight forward, just time consuming, it turned into a very complicated puzzle, which probably took me about 8 hours to finish in all, nothing like the Times prediction of just under two! Very satisfying once done though...
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Postby Rogue » Mon Feb 06, 2006 10:11 pm

I found this puzzle yesterday morning, and finished this morning. I’ve wanted to try an overlapping puzzle, but I hadn’t yet. I jumped onto the Times site, and I found one, just a little more extreme than what I was looking for originally. I couldn't pass it up though. I would say it took me somewhere between 6 and 8 hours, estimated based on numerous interruptions. The supposed "Time to Solve" of 115 minutes is insane. And forget about trying to do this thing on paper. Aside from having to blow it up just to fit in all the little numbers, it’s a lot easier to work electronically in a spreadsheet. It’s easier to check it’s accuracy that way too.

Sorry for the partial ranting – forum newbie.
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