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.

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1answer
83 views

What should be my next valid move?

That's the stage I'm now. I am looking at G block (one in left down corner) 4,5 value. I couldn't decide if it should be 4 or 5. How do I decide? And, am I looking at the right place? Any alternate ...
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Save the Eggs! - An Angry Birds Puzzle (Part 2)

⬅️ Angry Birds 1 After saving the eggs, the birds are more cautious. Good News! You can finally relax and enjoy the birds’ hospitality. Unfortunately for you, you’re not the only visitor in town. ...
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1answer
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Finding a number in this sudoku

I have been trying this sudoku for nearly 5 hours now but im unable to find any number further...If anyone could help me out i would be really grateful.. Note: The numbers in black are the prefilled ...
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Do multi-way jigsaw sudoku exist?

A Jigsaw sudoku is like a regular sudoku, but with uneven shapes instead of 9 squares. However, they still have the normal rules for rows and columns. Would it be possible to have a jigsaw sudoku ...
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How to solve this Sudoku?

Here is the sudoku - I could think the following only. The top number box 3 coloumn wise should have some number - 6,7,3 (in some order). The box 3 column 2 -- 2,5,8 ( in some order), and box 3 ...
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1answer
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Maximize 'chains' in a Sudoku

Yet to be solved. Take 2 numbers such that $N, M \in \{1,2,3,4,5,6,7,8,9\}; N \ne M$. Start with a solved 9x9 Sudoku grid. Find any $N_1 = N$. Find an $M_1 = M$, in the same row as $N_1$. In the ...
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Why is this considered to be “The World's Hardest Sudoku”?

NOTE: This is in reference to an existing question which I feel is poor and off-topic. In the spirit of "shaping the site while in private beta", I wanted show how the question can be re-phrased and "...
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An Incomplete Puzzle

I'm sorry to offload some of my work as the puzzle creator on to you solvers. (No, I'm not.) At least there's only one clue missing, right? EDIT: When the puzzle is ready to be solved, there will be ...
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1answer
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Trying to build a sudoku related puzzle box, struggling to ensure that there's only one solution

I want to build a specific puzzle box. The physical side I have down, but I'm struggling with ensuring that there's only one valid solution. The box consists of 9 freely rotating bands, inscribed ...
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Do there exist Graeco-Latin Square style puzzles?

Sudoku, KenKen, and Skyscrapers are three examples of Latin square puzzles. In all three, players are challenged to complete a Latin Square, a NxN grid (typically 9x9) in which the numbers 1-N appear ...
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How to solve this puzzle?

I have solved the sudoku. Scratching my head on the second part. Any hints? It is not picked from any competition. One of my office colleagues usually post these types of puzzles on emails for fun ...
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Happy Pi-Day! Try to solve this “PiDoku”

To celebrate the Pi-Day (3/14) adequately, a challenging math puzzle must not be missing. Rules: Fill in the numbers 1-9 exactly once in every row, column, and region. On top of that, you need to ...
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Sudoku Construction Question

I'm one of a group of people building a big puzzle hunt. I have what I think is a pretty good idea for a puzzle, but I'm having trouble constructing it. Basically, what I need to do is make a sudoku ...
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Sudoku puzzle - where to go next?

Above is a link to a half-solved sudoku puzzle. I tried to fully solve it but just cant figure out what to do now. Source: Sudoku-Branium studios It is an app on google playstore.
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SUDOKU What next? [closed]

I have solved up to this point. How do I proceed without guessing?
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Can a 9x9 sudoku with sum 45 and square sum 285 of (rows, columns, 3x3) not be valid? [closed]

I have created a program that checks if a Sudoku solution is correct. It tries to do so by checking the following: Rows, columns, 3x3 grids if the sum of the numbers is 45 $(1+2+3...+9=45)$ Rows, ...
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What are the criteria for determining the difficulty of Sudoku puzzle?

What are the criteria for determining the difficulty of Sudoku puzzles? Is it a subjective estimation based on the author's experience, or are there any precise guidelines? For example, there are ...
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Japanese Fusion Alphabet Soup

The Dish... ...is an intriguing blend, with a base of classic Western flavours, and a twist of the Orient at its heart. The Ingredients... ...are diverse and are combined in such an unexpected - ...
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Sudoku with chess queen rules

This is a unique sudoku. With Rules : Common sudoku rules apply. Numbers 1,2,3 have an additional rule, they are also chess queens. If all others numbers removed, the 1s do not attack each other ...
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Double n-queen puzzle, with sudoku rules

Put 9 blue queens and 9 pink queens, with rules : If the blue queens removed, each pink queens do not attack each other. If the pink queens removed, each blue queens do not attack each other. Each 3×...
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Tetromi-nuri-doku

Note: This puzzle was inspired by the one here, by Mike Q. Every square in the grid above, when the puzzle is complete, has a number between 1 and 9 in it and either is shaded or is not. Each 3x3 ...
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This is a crossudoku

So, this is a crossudoku. It is the same as a sudoku - same rules apply. However, you have been given crossword-like clues for part of the numbers on the grid. Some of the clues may have multiple ...
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What should be used to solve the next step of this sudoku puzzle

How to solve the next step in this sudoku ? I tried X-wing, hidden pairs and many other popular techniques found here http://hodoku.sourceforge.net/en/tech_hidden.php
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Special Sudoku, with windows pattern

Solve this Sudoku, with rules : Every blue square means, it is the left-top of a 3x3 block with each numbers [1 to 9] appearing only once there. There is only one unique solution. Check the example. ...
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What technique should be used to continue with this sudoku

I searched for x wing and the bone. Im thinking colors but not sure.
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Solve this Subtraction sudoku!

This is subtraction sudoku. The rules are basically the same as common Sudoku, but with a few additions. In the row, the number in the orange box is the difference when its left side (sum of 3 ...
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1answer
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Write digits 1 to 9 in the table, each pointing to next 3x3 grid

Write 1 to 9 digits in an empty Sudoku table with these rules (similar to 9-Queen problem): There are 9 Boxes indexed from 1 to 9 in the image below. and each box has a 3x3 grid child. Every two ...
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What do chess and wordoku have to do with each other? - Clue Thirty-One

<<---First clue <---Previous clue (?) "Aha! That's it," you exclaim, still holding the papers. "The answer is obviously [redacted]." Having figured out the answer, you start looking over the ...
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Another Determinant Sudoku

sudoku-determinant have been described well here : The Determinant Sudoku I have created another one. Number in the center is the value of the determinant Numbers 0 to 10 are the values of the ...
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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 ...
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1answer
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An EMIRP Game/ Puzzle for Prime enthusiasts

As most math enthusiasts know, EMIRPs are Prime Numbers which are also prime numbers when reversed. Like 17 which when reversed to 71 is also a prime number. Here is a Game or Puzzle based on 5 ...
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is there any sudoku puzzle combined with magic square?

As everyone know in Sudoku sum of each row and column is 45. so all Sudoku solutions are some kind of magic square. but my question is: Have anyone seen a Sudoku puzzle combined with the magic ...
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Sudoku difference between x wing and double pair

Double Pairs and X Wing are listed as different techniques here (former is a medium and later a master technique). The only difference I can see is double pairs are restricted to two neighbor blocks ...
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Tetromino Sudoku

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids The grid below, when filled in, forms a valid Sudoku grid. It can also be filled in like a LITS (nuruomino) puzzle without the 1x4 ...
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Arrange to get sum of 450 when it is added row wise and column wise

I just came across a maths puzzle,where i should get the sum of 9 numbers(multiples of 10) to be 450 both horizontally and vertically in a 9x9 matrix. Picture attached for reference:
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What is the maximum number of solutions a Sudoku puzzle can have?

I've seen Sudoku puzzles that can be solved two different ways. Referring to a traditional 9x9 grid: Is it possible for a Sudoku puzzle to have more than two solutions? If so, what is the maximum ...
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Who am I??? Wait, isn't this a sudoku?

Jmw jrr qtlf tv ee M6SXr rro tr kz r tyr. Can you find out who I am? Hint 1: Hint 2:
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The Numberphile Heist (part 1)

Hello Puzzling Stack Exchange! While part 1 of the PSE School of Enigmatics remains unsolved, I've got part 1 of another puzzle series for you to solve. I'm in no way affiliated with Numberphile; ...
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Nested sudoku in entrance exam

My university set this question in 2013's entrance exam. Also the red boxes include from 1 to 9. What's the solution for this sudoku?
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The Determinant Sudoku

The determinants of $2\times 2$ matrices are calculated this way: $$\det\begin{bmatrix}a & b \\c & d \end{bmatrix}=ad-bc$$ And here's the sudoku-determinant puzzle: What's the solution for ...
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Minimum steps to verify a Sudoku solution

When checking if a 9x9 Sudoku solution is valid in the absence of an answer key it may not be necessary to check every row, column and 3x3 box. What is the minimum number of items (rows, columns, or ...
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1answer
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Skeleton sudoku, the second

I've already set one skeleton Sudoku. Here's a rather harder one. (Nonetheless, it should be within the realms of what can be done by hand; I solved it manually myself to verify that there was only ...
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Special 5x5 Sudoku-like table

This is a special 5x5 Sudoku-like table. Each row, column, and diagonal contains digits from 1 to 5 (including diagonals obtained by wrapping around the edges). To filter duplicates (by rotation, ...
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A spartan skeleton Sudoku

A skeleton crossword is a crossword where the black and white squares aren't given; you have to deduce them. Here's a generalisation of that idea to the Sudoku puzzle. Here's a 4 by 4 grid, with four ...
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1answer
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What will be the last Sudoku number to be filled?

When I am completing a Sudoku puzzle, there are always two last numbers to fill. Maybe it is just my puzzle solving approach or maybe it is inherent to Sudoku. I got wondering, would everyone who ...
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Sudoku net that is always solvable

A sudoku net is a 9x9 grid where every cell is either (blank) or has a cross (block). A random solved sudoku is chosen. The net is placed on top of the sudoku (in any of the 4 ways). We can only see ...
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Sudoku with only 8 predefined numbers

Have fun with my self-made Sudoku puzzle. Solve this Sudoku puzzle using the standard Sudoku rules: Fill any row, column and bold-framed area with the numbers 1 to 9. Hint: It is not as difficult as ...
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Introducing: Sudoku-Janpu

This is an entry into the 29th fortnightly topic challenge - Retrograde Analysis. Scenario: Alice and Bob were playing a game of Sudoku-Janpu. Alice: I win. Bob: (looking at the board) Oh man, not ...
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Why does generating a Sudoku work in lines, but not in a random pattern?

So, I'll preface this by saying that I am not 100% whether this fits better here or on SO. That said: I've been trying to generate Sudokus using a backtracking algorithm to fill in the whole thing. ...
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Sudoku board hint (part 2)

Don't worry, this is the last hint I'll ask for. I've looked for any position that could exclude others, and what's left is perfectly symmetrical. I've even tried mentally choosing some options to ...