Questions tagged [sudoku]

A Sudoku is a puzzle consisting of a grid to be filled with symbols, such that each constraining unit contains each symbol exactly once. The typical example is a 9x9 square to be filled with the numbers 1 to 9, where the constraining units are rows, columns, and 3x3 blocks.

Filter by
Sorted by
Tagged with
13
votes
1answer
300 views

Why would I need a Lamborghini Rebenton?

The proper word to use as the ninth symbol is in Berlin (3) Daily Hint 1:
11
votes
2answers
276 views

Specialist sudoku

I know y'all want to be generalists or something, but here's a little sudoku for (geography) specialists. Enjoy. ABRAU ⋅ AGANTON ⋅ AKUSEKIJIMA ⋅ ALICE HOLT ⋅ ALTENBURG-NOBITZ ⋅ ANJEDIVA ⋅ ...
8
votes
1answer
207 views

This new puzzle type needs a name {5}

I believe I have invented a new type of puzzle... What is its name? Colour-blind-friendly version available here. Begin by solving the 9x9 sudoku; each of the 9 symbols ...
5
votes
1answer
120 views

Against the Grain, Salt to the Sea: Sudoku

Against the Grain, Grain of Salt, Salt to the Sea, Sea...badge? What Badge? Of course, guessing is not fun, right? Anyway, congratulations to anyone who get this! :D
5
votes
1answer
135 views

Just Another Sudoku for PSE

Crafted with love for PSE, <3
18
votes
1answer
875 views

Your Task Is to Create the World's Hardest Irregular Sudoku!

Ahem, let's formalize your task... A Sudoku is a puzzle consisting of a grid to be filled with symbols, such that each constraining unit contains each symbol exactly once. The regular Sudoku is a $9 \...
12
votes
1answer
715 views

This new puzzle type needs a name {4}

I believe I have invented a new type of puzzle... What is its name? Begin by solving the 16x16 sudoku; each of the digits 1-16 must appear exactly once in each row, column and thick-bordered 4x4 ...
1
vote
2answers
94 views

How do I go ahead in this?

Got this from daily challenge of sudoku app.
-3
votes
1answer
249 views

Traps on Sudoku grids [closed]

Let's have a 9x9 Sudoku grid. Where the dots are shown above, you are allowed to put the numbers 2, 4, 6, 8. Each of these appears seven, seven, seven, and six times. It does not matter which number ...
8
votes
2answers
451 views

Setka - Complete grid using clues and sudoku-style logic; Theme - Halftime

This is a Setka puzzle; you can find more (along with a more detailed explanation of the rules) at our website, linked from our profile. How to play Setka, the short version: Answer each clue using ...
6
votes
6answers
400 views

Good resource for daily Sudoku Puzzles

I love solving puzzles, It keeps my brain active. Previously I used to solve newspaper Sudoku which were fairly easy. Then I solved some interesting puzzles in the ...
4
votes
2answers
239 views

What is the maximum number of numbers a sudoku can have and have more than one solution?

I was watching this video where he talked about how scientists found the minimum number of numbers a Sudoku can have and still have exactly one solution. This led me to think of the opposite - what is ...
3
votes
1answer
141 views

Can I swap two “yellow” corners on the same side?

The bottom two layers are solved, and the cross has been formed on the bottom layer. I am putting the corners in, ready to orientate them correctly, but I have two corners which need swapping. (The ...
17
votes
2answers
248 views

Queens of the Square Sudoku Table

. 6 . | 8 . 3 | . 7 . . . 1 | . . . | . 6 9 7 . . | . . . | . . 5 ---------+---------+-------- . . . | 9 . . | . 1 . . . . | . . . | . . 4 . . 5 | . 1 . | . ...
74
votes
1answer
4k views

This new puzzle type needs a name

I believe I have invented a new type of puzzle... What is its name? Colour-blind-friendly version available here. Begin by solving the 16x16 sudoku; each of the digits 1-16 must appear exactly ...
24
votes
4answers
1k views

Another new puzzle type needs a name

For an example of how this type of puzzle works, see here... I believe I have invented another new type of puzzle... What is its name? Colour-blind-friendly version available here. Begin by ...
11
votes
2answers
516 views

Compoundoku wants BIG

Rules of Compoundoku: Solve both left and right Sudokus. In addition, the board below them is the Compound Board of both Sudokus. Each number on the Compound Board should tell either: (1) ...
23
votes
2answers
1k views

Introducing: Compoundoku!

Rules of Compoundoku: Solve both left and right Sudokus. In addition, the board below them is the Compound Board of both Sudokus. Each number on the Compound Board should tell either: (1) ...
9
votes
1answer
229 views

How much information can we get from a thermometer?

A fairly common Sudoku variant is so called "Thermometer" Sudoku. In this variant arrows with a rounded end (which look like a thermometer) are added to the grid, with the rule that the numbers on ...
2
votes
1answer
127 views

Sudoku - can’t get any further

What technique am I missing here? I have try all the usual naked pairs etc.
3
votes
1answer
119 views

What is the technique I should use now to go ahead?

This is a partially filled sudoku from the Sudoku Expert app. I thought I learnt all tricks and techniques. But clearly there is something I don't know about.
10
votes
3answers
689 views

A Family Reunion

Names have been changed to preserve anonymity A group of 25 people, A to Y, arrived at Z's door to celebrate the family reunion. They each had something to show off. Z: I know you're all excited ...
3
votes
2answers
798 views

Unsolvable sudoku net with maximum blocks

Definitions For a $9\times9$ grid $G$ (not necessarily respecting sudoku rules), a subset of cells $S$ is defined to be sudoku-friendly if the values in $S$ do not contradict the rules of sudoku. ...
36
votes
6answers
1k views

Sudoku embedded in a Kakuro

In addition to standard Kakuro rules, the grey shaded cells must form a valid Sudoku solution. One sum in this puzzle has been corrected from 28 to 23. Fortunately, it was in a location that nobody ...
3
votes
4answers
383 views

Help with a sudoku puzzle

I would really appreciate some help because I spent more than hours finding another number. It is supposed to be a very hard one but I started well and according to the key, my numbers are correct. Do ...
4
votes
2answers
137 views

Sudoku, unclear next logical step?

Solved up until here, I took the sudoku through an online solver and it seemed to use a guess and check strategy? Is that the only way of getting the solution or am I missing something?
5
votes
1answer
149 views

All That Remains Sudoku

. 2 . | . 7 . | . . 9 . 9 8 | . . . | . . . 3 . . | 9 . . | . . . ---------+---------+-------- 2 . 7 | . . . | . . . . 1 5 | 7 . . | . . . . . . | 1 5 8 | . ...
8
votes
1answer
238 views

Whirlwind of the Square Sudoku Table

. . . | . . . | . . . 6 . . | . . 1 | . 2 . . . . | . . . | . . . ---------+---------+-------- . . 7 | . . . | . . . . . . | . . . | . . . . . . | . . . | . ...
7
votes
1answer
264 views

Knights of the Square Sudoku Table

8 . . | . . . | . . 6 . . 4 | . . . | . . . . . . | . . . | 9 1 . ---------+---------+-------- . . . | . 2 . | . . . . . 9 | 3 . . | . . . . . . | . . . | . ...
4
votes
1answer
139 views

What technique I should use now? [closed]

I am stuck here. I don't want solution for this, I just want to know the name of technique which will be used here to go ahead.
7
votes
2answers
175 views

Spidoku - Fill in the rest?

Each of the eight segments of the spiderweb should be filled with a different number from 1 to 8, in such a way that every ring also contains a different number from 1 to 8. Some numbers are already ...
0
votes
3answers
178 views

Sudoku Move Marked Wrong, Seems Legal: Software Bug? [duplicate]

The included screenshot shows an attempted Sudoku move. The computer is marking it incorrect. There is no other 7 in the row, column, or 3x3 cell. What gives?
10
votes
2answers
582 views

Another Colombian Sudoku

Solve the Sudoku on the left, where the usual rules apply. The dots outside the board on the right indicate how many cells in the corresponding column or row of that board contain precisely the same ...
3
votes
3answers
110 views

What patterns could be applied in order to solve a Sudoku?

Related to this Q&A. I am looking for a pattern that could be applied in order to solve this Sudoku. The current patterns that I apply: Ensure that every digit appears once in every block Ensure ...
3
votes
1answer
138 views

Can you help me with a logic to solve this puzzle?

I know the concept of pairing and removed pairs but what other concepts should I use to solve this?
3
votes
2answers
136 views

Excluding number in a sudoku scheme

I have the following scheme: Please look at the lower left subgrid. The 8 may go in R7C1 or R9C1. If I put the 8 in R7C1 I'd have a 4 in R9C7 and a 5 in R8C7 If I put the 8 in R9C1 I'd have the ...
2
votes
1answer
153 views

What can be the next move without guessing in this almost solved Sudoku puzzle?

I am currently stuck at this puzzle where I can't think of the next move without guessing it. I was surprised to be in this situation after solving ~70-80% of the puzzle. I thought for all possible ...
3
votes
2answers
117 views

What am I missing in this Sudoku?

I think I am missing something in the instance below, since I could solve it only with a long-winded chain of deductions starting with the assumption that (coordinates are (row,column)): and ...
4
votes
1answer
112 views

Sudokus and combinatorics

Considering your suggestions, I have redrawn the 12 X 12 Sudoku so that the twelve rectangles are now visible. The question remains the same: Can someone construct a 12 X 12 Sudoku with the following ...
7
votes
6answers
1k views

What next step can I take in solving this sudoku?

There are lots of pairs and I don't want to assume any values.
3
votes
0answers
175 views

Minimum amount of clues for a 16x16 sudoku

I know that 17 is the minimum for a standard 9x9 (3x3 squares), but what about a 16x16 (4x4 squares) sudoku?
13
votes
1answer
400 views

Sandwich Sudoku: First 12 digits of pi

Sandwich Sudoku, or "Between 1 and 9 Sudoku", is a variant of Sudoku. A YouTube channel introduced this variation. Rules: Standard Sudoku rules. Place numbers from 1 to 9 in every row, column, ...
3
votes
5answers
547 views

What is the best way to solve this 6x6 sudoku? [closed]

I eventually used a trial and error method to solve it: Assume B1 = 2 C2 and F1 = 4 C3 = 2 F3 = 6 There are no candidates left for A3 This let me set B1 = 4 and hence solve the puzzle. But is there ...
4
votes
3answers
472 views

Was “Crook's algorithm” for Sudoku really only developed in the 21st century?

The following algorithm for simplifying (and very often completely solving) Sudoku puzzles: Label each cell with the set of all possible values it could take. Pick a row/column/block and for a value ...
6
votes
3answers
3k views

How can I solve this sudoku?

I've almost finished this hard sudoku, but I cannot finish it without guessing or making multiple blind steps to see if I'm wrong or not. Even https://www.sudoku-solutions.com/ gives up and says "...
11
votes
1answer
3k views

Minimum number of clues for a sudoku puzzle

In a sudoku puzzle, what is the absolute minimum number of clues that must be given to specify a layout with a unique solution? Is one in each row, column, and box (9 total) necessary or sufficient?
2
votes
0answers
102 views

Most objective online linkable sudoku grader?

A Sudoku's difficulty level is often the first thing readers notice about a puzzle. For questions and answers showing a puzzle it would be nice to have a relatively objective linkable tester. I've ...
7
votes
1answer
176 views

Maximum number of disjoint clue-sets that determine the same Sudoku solution?

"Do sudoku answers always have a single minimal clue set?" No. Solved Sudoku puzzles may have more than one set of disjoint clue-sets. And those clue-sets can vary in difficulty, so one might be ...
3
votes
0answers
92 views

Is there a Sudoku answer that has only a single minimal clue set?

User Abigail comments on the titling of "Do sudoku answers always have a single minimal clue set?" : I'd be surprised if there were a Sudoku which doesn't have at least 2 disjoint clue-sets. Well ...
15
votes
2answers
3k views

Do sudoku answers always have a single minimal clue set?

Suppose we have a solved sudoku, which was started from a minimal set of clues to its unique solution, i.e. 17+ numbers in specific locations, which we'll call set1. Is there a set2, (or set3, etc.), ...

1 2 3 4 5