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Questions tagged [grid-deduction]

Puzzles such as Sudoku or Kakuro, where the final state of a pre-existing grid must be deduced logically through clues placed within and/or around the grid. Use with the [logical-deduction] tag. For puzzles where you are given a list of clues which can be used to compose a grid to solve them logically, use the [logic-grid] tag instead.

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14 votes
2 answers
1k views

Going around in circles

Solve the grid. Then solve the grid again. The answer can be one or two letters long.
Jujustum's user avatar
  • 4,019
18 votes
2 answers
1k views

Nonconsecutive Anti-Knight Fillomino?

Rules of Fillomino: Fill in all empty cells with numbers under the following rules. Divide all of the board into blocks. Fill each block with the same number horizontally or vertically. Each block ...
Bubbler's user avatar
  • 15.6k
17 votes
1 answer
1k views

66: Luftballons

This is part 66 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a Dosun-Fuwari puzzle. Place some balloons (white circles) and anvils (...
Jafe's user avatar
  • 78.1k
16 votes
1 answer
2k views

What's the one digit you can fill in this partially hidden Sudoku?

A few weeks ago, I challenged some people to solve the puzzle I made. Two of them took it more or less seriously, but couldn't find the right solution. Now they are excited to see whether or not ...
Paul Kolk's user avatar
  • 270
2 votes
1 answer
190 views

A Framework puzzle

About Framework puzzles: A Framework puzzle is similar to a Fill-in puzzle, except there is no rigid crossword-style grid, the tradeoff here being that you get fewer hints for placing (in this case) ...
CrSb0001's user avatar
  • 2,423
20 votes
2 answers
719 views

Torus Flow Free

Rules: this is a flow free warp puzzle with a 9x9 grid. connect the respective letters together with lines that travel orthogonally through the centers of grid cells. additionally, the sides of the ...
Omega_3301's user avatar
4 votes
1 answer
418 views

Are circles required on the edge of the grid? Part 2

This question is a follow up to a previous question: Are circles required on the edge of the grid? The image below is a puzzle from the FlowFree app. Notice there are no colored circles on the edge of ...
Will.Octagon.Gibson's user avatar
10 votes
1 answer
324 views

3-clue 5x5 Hidato

Rules Fill the grid with numbers 1-25 such that consecutive numbers are adjacent orthogonally or diagonally Try solving it in Penpa There are only about a dozen 5x5 Hidatos with only 3 clues. (...
Tom Sirgedas's user avatar
  • 1,558
12 votes
1 answer
653 views

Bare Bones – a semi-DIY crossword

This is part 64 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a semi-DIY crossword. Shade some cells in the grid so that the grid has ...
Jafe's user avatar
  • 78.1k
11 votes
2 answers
1k views

New record for minimally clued 7x7 Hidato (now with 6 clues!)

Rule of Hidato: Fill the grid with consecutive numbers such that they connect orthogonally and diagonally. Solve the following three Hidato puzzles. 8 clues 7 clues 6 clues You can solve these on ...
Bubbler's user avatar
  • 15.6k
5 votes
1 answer
173 views

Current record for minimally clued 7x7 Hidato (16 clues)

Background Back in March, I posted this question on the Puzzling Stack Exchange asking how many clues were needed to create a 4x4 Hidato puzzle with a unique solution. Sometime after this, I took a ...
CrSb0001's user avatar
  • 2,423
8 votes
6 answers
1k views

Are circles required on the edge of the grid?

The image below is a puzzle from the FlowFree app: The image below is my solution to the above puzzle: The rules stated in the app are: Drag to connect matching colors with pipe, creating a flow. ...
Will.Octagon.Gibson's user avatar
5 votes
1 answer
461 views

Oh no, my chocolate banana puzzles are not unique!

There is a hidden message (7, 2) inside the solutions of the nine puzzles. An answer will only be accepted if it correctly identifies said message. Here are the Chocolate Banana puzzle rules. Each ...
Sny's user avatar
  • 3,185
6 votes
2 answers
543 views

Create an empty 8x8 One Up puzzle with a unique solution

Rodolfo Kurchan created a wonderful new grid puzzle called One Up that you can play on his website. There is one main rule: Each horizontal and vertical sequence of N cells between walls, must contain ...
Dmitry Kamenetsky's user avatar
16 votes
2 answers
853 views

When in Rome... – a deconstruction sudoku

This is part 63 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a sudoku deconstruction puzzle. Draw eight non-overlapping rectangular ...
Jafe's user avatar
  • 78.1k
27 votes
3 answers
1k views

Try Triling ("Triangular-Tiling")

You are given a grid. Some of the cells in the grid are labelled with positive numbers. You must partition the grid into triangles. There must be a triangle for each labelled cell Each cell must be ...
user23087's user avatar
  • 912
5 votes
2 answers
312 views

Number of 3x3 One Up puzzles

Rodolfo Kurchan created a wonderful new grid puzzle called One Up that you can play on his website. There is one main rule: Each horizontal and vertical sequence of N cells between walls, must contain ...
Dmitry Kamenetsky's user avatar
2 votes
1 answer
168 views

Minimally clued 2x3 Sudoku

Beginner puzzleThis puzzle is intended to be suitable for people who are new to puzzle solving. However, both experienced solvers and new solvers are welcome to post solutions to this puzzle. ...
CrSb0001's user avatar
  • 2,423
10 votes
2 answers
1k views

One Up 8x8 puzzle

Rodolfo Kurchan created a wonderful new grid puzzle called One Up that you can play on his website. There is one main rule: Each horizontal and vertical sequence of N cells between walls, must contain ...
Dmitry Kamenetsky's user avatar
3 votes
1 answer
201 views

Are draws possible in the game Nakatta?

I'd like to know if this game can end in a draw: Nakatta is a connection game for two players: Black and White. It is played on the intersections (points) of an initially empty square grid (board). ...
Luis's user avatar
  • 145
25 votes
1 answer
1k views

A genius Margonon!

To solve the puzzle below, the standard rules of a fill-a-pix (or mosaic) apply: Paint the squares around each clue black so that the number of painted squares, including the square with the clue, ...
Lezzup's user avatar
  • 7,382
3 votes
1 answer
155 views

Themed 7x21 Chocona

Chocona rules differ from Chocolate Banana rules. There is a hidden message inside the solution of the puzzle. An answer will only be accepted if it correctly identifies said message. The message is ...
Sny's user avatar
  • 3,185
5 votes
1 answer
196 views

Themed 13x9 Chocolate Banana

There is a hidden message inside the solution of the puzzle. An answer will only be accepted if it correctly identifies said message. P.S. I promise this is my last Chocolate Banana puzzle of the ...
Sny's user avatar
  • 3,185
11 votes
2 answers
513 views

Prime and Composite 6x6 Chocolate Banana

The number of chocolates (black regions) is prime. Normal Chocolate Banana rules apply. Rules: Paint some of the cells black. Black cells linked orthogonally must always form a rectangle (or a ...
Sny's user avatar
  • 3,185
9 votes
1 answer
248 views

9x13 Chocolate Banana Puzzle $\pi=\frac{43}{3.7^2}$

Since 37 is my favorite integer and π is my favorite number, here's another puzzle: Normal Chocolate Banana rules apply. Rules: Paint some of the cells black. Black cells linked orthogonally must ...
Sny's user avatar
  • 3,185
5 votes
1 answer
265 views

A final Colombian Sudoku... for the time being

This too is a Colombian Sudoku by Xavier Castillo. The usual rules apply. The dots outside the board on top indicate how many cells in the corresponding column or row of that board contain precisely ...
Bernardo Recamán Santos's user avatar
7 votes
1 answer
269 views

11x13 Chocolate Banana Followup

Your goal is to maximize the absolute difference of the numbers marked ?. (? marks indicate region areas. They may or may not ...
Sny's user avatar
  • 3,185
3 votes
1 answer
278 views

Stuck on "The Persistence of Memory"

The Persistence Of Memory The Memory Labyrinth Rules You are currently just behind the door in the bottom right. You must walk through each of the other rooms before returning to the first room. ...
ApexPolenta's user avatar
  • 2,964
14 votes
1 answer
1k views

10x10 Choco Banana

Normal Chocolate Banana rules apply. Rules Paint some of the cells black. Black cells linked orthogonally must always form a rectangle (or a square). Non-blacked cells linked orthogonally must not ...
Sny's user avatar
  • 3,185
4 votes
2 answers
250 views

Another four 3D masyu

This puzzle is inspired and descended from Brain-breaking 3D masyu Here the exact copy of rules, for convenience: This is a three-dimensional masyu puzzle.1 The five squares depict the layers of a $...
Alexey Birukov's user avatar
7 votes
2 answers
826 views

A Difficult Colombian Sudoku?

This Colombian Sudoku is by Xavier Castillo. Usual Sudoku rules apply. Additionally, digits on each of the two diagonals must all be different. The dots outside the board above indicate how many cells ...
Bernardo Recamán Santos's user avatar
13 votes
1 answer
552 views

🐍 In the Loop 🐍

Follow the ouroboros down valleys and over mountains. Is it even going anywhere? EDIT (7 days after initial posting): The grid and Penpa+ link have been updated to an easier version, with more numbers ...
DanDan面's user avatar
  • 1,044
5 votes
1 answer
431 views

Help with Star Battle puzzle

I made it through all the easy levels without ever having to consciously divide the whole grid into specific regions. I've seen that this is a common technique, but it confuses me even more when ...
gemmabomma's user avatar
12 votes
2 answers
462 views

A Crabby Sudoku

I present a *deep breath* Even-Odd TetroThermoDoku. From the back of the name to the front: Rules Sudoku: Fill each cell with a digit 1-9 such that no number repeats in any row, column, or 3x3 heavy-...
bobble's user avatar
  • 10.4k
13 votes
1 answer
598 views

Plumbing Issues

This is part 59 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a Pipes puzzle (also known as Net, FreeNet and NetWalk). Rotate some cells ...
Jafe's user avatar
  • 78.1k
18 votes
2 answers
1k views

A small board-puzzle

Place pieces (red) on the board, so every piece is adjacent to 4, 5 or 6 other pieces. I've created this puzzle myself playing around with cellular automatons.
Dromlius's user avatar
  • 185
20 votes
2 answers
942 views

Masyu: Four Colours

Draw four separate loops in the grid, one blue, one green, one grey and one red. Loops connect centres of cells horizontally and vertically and cannot cross over themselves or share any cell with each ...
Jafe's user avatar
  • 78.1k
3 votes
1 answer
421 views

Continue in 6x6 Towers puzzle

How can I continue with this Towers puzzle?
Alex Eh's user avatar
  • 31
10 votes
1 answer
1k views

Cover me, I'm going in!

This is part 58 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a diagramless checkerboard crossword. Empty cells are either blue or white;...
Jafe's user avatar
  • 78.1k
15 votes
1 answer
820 views

Riverboat Soufflé

This is part 57 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a bicolour Masyu puzzle. Draw two separate loops in the grid, one red and ...
Jafe's user avatar
  • 78.1k
1 vote
1 answer
169 views

What can I deduce about this daily Skyscrapers? (Mar. 18, 2024, 5x5 Easy)

So I have been using a site called Brain Bashers, which is a site filled with logical deduction puzzles, because I like trying to master different logical deduction puzzle types. I have finished the ...
CrSb0001's user avatar
  • 2,423
25 votes
3 answers
2k views

a few signposts

Assign an integer (1 through 16) to each cell so that: 16 is in the cell with the star; and each integer's arrow points to its successor (i.e. the next integer), though not necessarily in the ...
msh210's user avatar
  • 12.9k
7 votes
2 answers
361 views

Product = Sum Sudoku (Royal Statistical Society Christmas Quiz 2023)

Normal Sudoku rules for this grid size apply. The product of the numbers on each pink diagonal equals the sum of the numbers in the blue square. This puzzle is from the now closed contest at: https:/...
Will.Octagon.Gibson's user avatar
0 votes
0 answers
202 views

Continue with sudoku - how do I scan for next steps?

I filled some cells, but am stuck here. I cannot go any further. How do I advance? How would I scan the Sudoku to recognize next steps? I've taken the puzzle from https://play.google.com/store/apps/...
Abbas Baghirov's user avatar
6 votes
1 answer
171 views

A hard(?) 15-X puzzle

Below is the puzzle I came up with before writing Create a 15-X puzzle with a unique solution. Rules of the puzzle: A 6x6 grid is given. Fifteen cells are marked with an X. Use polystrips of lengths ...
Bubbler's user avatar
  • 15.6k
13 votes
2 answers
235 views

Create a 15-X puzzle with a unique solution

Background Last week, Brandan came up with a grid-deduction genre about filling a 6x6 grid with polystrips of lengths 1 through 8, using each length exactly once. A polystrip cannot bend twice in a ...
Bubbler's user avatar
  • 15.6k
3 votes
1 answer
238 views

Minimally clued 4x5 Hidato (4 clues)

Puzzle attribution: Me :) Background So as you might or might not know, I have been studying the minimum number of clues needed to force a unique solution in Hidato for variously sized boards. I ...
CrSb0001's user avatar
  • 2,423
6 votes
1 answer
199 views

5x5 Hidato with 4 single-digit clues

Goal of Hidato: Fill in a grid with a series of consecutive numbers that connect each other horizontally, vertically, or diagonally. Yesterday I posted New record for minimally clued 5x5 Hidato, ...
Bubbler's user avatar
  • 15.6k
9 votes
2 answers
295 views

How do I constrain a puzzle and keep a singular solution?

I am tinkering with a puzzle framework that has the following rules: In a 6x6 grid of squares, arrange 8 strips of connected squares such that there exists exactly one strip of every length (i.e. a ...
Brandan's user avatar
  • 143
11 votes
3 answers
662 views

New record for minimally clued 5x5 Hidato

CrSb0001 has been studying the minimum number of clues to force a unique solution in Hidato for variously sized boards. They came up with a 5x5 Hidato with 5 clues but it was found that it has ...
Bubbler's user avatar
  • 15.6k

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