# Tag Info

35

This seems to fit: The initial step was to replace all 1's (red) with a 2 (black) and all 9's with an 8: Then, whenever a red number was +/- 1 of a black number which was on the same row, column or box, the red number was changed to its other possible value. E.g. if a red 6 was on the same row as a black 5, the red 6 was changed to a black 7 as it couldn't ...

32

I have been asked by a couple of people to show the creation process for this puzzle, so here we go: Also if people want to see more of these strange, Sudoku mash ups then I'll be more than happy to combine some new types :) Wrap-up: The Making Of This Samurai Pseudoku This is not a solution to the puzzle, but provides notes from its poster. This type of ...

25

This puzzle is certainly not Solving the crossword: The clues: Then solving as a 'Wordoku': (Not posted logical path as it is quite straightforward, but can if needed)

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COMPLETED GRID REASONING First steps: Moving on: Some Sudoku forcing: Finishing up:

18

A naked single occurs when Basically, there will be numbers that rule out 8 of 9 possibilities. So for the 7 bottom right: As all the others are ruled out in various ways, it must be a 7. The strategy would be to look at a cell and go through 1-9 and see what is ruled out. If all but one number is ruled out, it must be that number! Hope this helps!

18

I am officially an idiot. I spent several hours figuring out brilliant deductions and got really good progress with many actual numbers on the grid, and even though I got stuck at places, there was always some clever bit that got me just that much forward. In the end, I was just about to fill the grid in two different ways to show that the puzzle must be ...

16

Step 1. Let's start with: So... Step 2. However, the basic rule of any sudoku says: So: Step 3. However, this is not a normal sudoku. So: So: Step 4. Now, the things get harder. But let's see that: So: Step 5. Further: Hence: So: Step 6. We have a: So: Step 7. Hence: Step 8. So: Step 9. So: Step 10. So: Step 11. So: Step 12. Step 13. ...

16

Solution (click to see large version): The first thing is to produce the following list: I: 1234 6789 II: 23 78 III: 3 8 IV: 4 V: 45678 VI: 678 VII: 78 X: 9 From that, standard Sudoku techniques apply. I'll just list some middle steps below.

15

Completed grid (cube?): Explanation: There were a LOT of deductions to make here. I'm not going to give step-by-step, but I will show several milestones along the way. I'll explain some of my favorite (read: head-bangy complicated) deductions and some common deduction types I used a lot. Unfortunately, my pictures and my favorite deductions do not always ...

15

Now Complete Answer The first thing to notice is: To represent the solution: The first steps: Moving on: At this point: Using the funky square: Some more funky square logic: Some perspective after sleep: One final logical step:

15

As others have seen, the 9 sudokus are generally unsolvable because they have numbers which repeat in rows and/or columns. However, there is one exception, which is the central sudoku. It turns out it is solvable and with a unique solution: There is something striking about the solution, namely that the central 3x3 square has a very nice ordering of its ...

15

From the SO answer to the essentially same question (test cases for Sudoku solver): You can find some large datasets for Sudoku benchmarking and testing in this project: https://github.com/t-dillon/tdoku See data.zip for the puzzles. See https://github.com/t-dillon/tdoku/blob/master/benchmarks/README.md for descriptions of the datasets, their sources, and ...

14

Completed grid: Reasoning:

13

Solution: Method:

13

Here is my attempt at solving this:

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The Solved Grid Also: Solution Method A general observation: The first deduction we can make is in: Continuing: Next: Working in row 6 from the top: Continuing in this row: Some small deductions from here: Now let's try to place the 9's: Moving on: Let's tackle the upper-left box: Notice two important properties of these solutions: Some more ...

13

Here is the solution

12

Should've known what I'd gotten myself into when starting, whew. Great puzzle! Really hard, but I hope I got everything right. 0th Step: Try to squeeze out everything we can by normal Sudoku first: 1st Step: 2nd Step: 3rd step: Last step:

11

Here's how I did it: Step 1: Step 2: Step 3: Step 4: Step 5: Step 6: Step 7:

11

This is a fantastic puzzle! Incredibly difficult, but with a really nice solution path. I have no idea how you managed to come up with this! Solution: How to solve: (This took me about 7 hours so my memory of early logic is fairly rusty, but I have explained as best I can) 1: 2: 3: 4: 5: 6: 7: And finally, cleaning up the right hand grid and entering ...

11

The final answer is: Step 1: Step 2: Step 3: Step 4:

10

Blimey, this took ages by hand! Method/Hints

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Step 1: Step 2: Step 3: Step 4: Step 5: Step 6: Step 7: Step 8: Note:

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UPDATE: It's a full solution now.

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Reasoning: From here: Next steps: Moving on: At this point:

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Step 1: Step 2: Step 3: Step 4:

10

I used the exact same logic for each picture here: With that in mind, some pictures, in order. I mostly completed two regions per picture. Step 1: Step 2: Step 3: Step 4: Step 5: Step 6 (and the solution): Not hard but quite enjoyable.

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Standard Sudoku rules Looking for the I-tetromino Looking for the T-tetromino Looking for the L-tetromino Looking for the S-tetromino

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R6C5 doesn't have anything ruling out it being a 6... but R4C5 could only be a 6. There are no other options for R4C5: placing a 1, 2, 3, 4, 5, 7, 8, or 9 would break the rules. You know you have to fill a box with some number, and that is the only one left. This is one of two basic Sudoku techniques, the "naked single" -- when a cell only has one ...

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COMPLETED GRID REASONING Looking up top: At the bottom: Finishing up:

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