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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7
votes
1answer
239 views

“Puzzle Waffle”

A black man, tilting his head in satisfaction and checking it was about lunchtime, entered the Sphinx Café in downtown Washington D.C. on a Friday out of boredom with his usual lunch haunt and greeted ...
8
votes
2answers
380 views

A Sudoku With A Trick

Normal Sudoku rules apply in this puzzle. This is an incredibly difficult puzzle to solve and has a very clever and ingenious trick in it. I request solvers to show their work at different stages of ...
14
votes
1answer
696 views

Up like a rocket ship

This is a Palisade (or 6 Cells) puzzle. The rules are: Thicken some of the pentagons' sides so the thick borders outline regions of six pentagons apiece. Any pentagon with a number in it indicates ...
16
votes
1answer
314 views

A Dotless Kropki

Rules of Kropki: Each row and column contains one occurrence of each digit from one to the size of the grid. All pairs of orthogonally adjacent cells containing numbers with a 1:2 ratio are marked ...
3
votes
5answers
803 views

Can you fill the cells by integers? [duplicate]

Can you fill the cells with integers so that all the equalities must be true?
11
votes
1answer
225 views

Stostone - Aoi's Big Birthday

Rules of Stostone: Shade exactly one stone, an orthogonally-connected group of cells, in each region. No two stones in different regions are adjacent. If a number is in a region, it tells the size of ...
3
votes
1answer
184 views

Quadruped Mosaic

This is a visual puzzle (known as "mosaic" or "fill-a-pix") with the same rules as MineSweeper: This puzzle has exactly 100 x 100 cells. The grid is to be filled with colored and ...
5
votes
1answer
221 views

A brain[expletive] sudoku

This is a Sudoku that is also a Brainfuck program. The standard rules of Sudoku apply. The same symbol can not appear twice in the same row, column, or 3x3 box. The grid should also form a functioning ...
18
votes
1answer
547 views

Slitherknot (Double Slitherlink)

This is a variation on the classic Slitherlink Puzzle. However, instead of creating one loop, you must create 2 separate loops. The two loops can not share any edges, however they can cross or meet on ...
8
votes
1answer
212 views

Gaps - Square Numbers

Rules of Gaps: Fill some cells with stars, so that each row and column contains exactly two stars. The stars cannot touch each other, not even diagonally. Numbers outside the grid indicate the number ...
13
votes
1answer
877 views

A walk after dark

This is a Palisade (or n-Cells) puzzle. The rules are: Thicken some of the squares' sides so the thick borders outline cells. One such cell comprises just one square; one cell comprises precisely two ...
8
votes
3answers
303 views

Toroidal Pipes Puzzle: T's and Bulbs Only

A continuation in the Pipes puzzle series. Problem statement for math nerds: Let $G(N)$ denote the graph consisting of cardinally adjacently linked lattice points on an $N \times N$ toroidal grid. For ...
15
votes
1answer
1k views

When you stop at the top of a Ferris wheel

This is a Palisade (or Ten-Cells) puzzle. The rules are: Thicken some of the squares' sides so the thick borders outline cells of ten squares apiece. Any square with a number in it indicates how many ...
13
votes
1answer
447 views

Windmill: A Masyu Puzzle

The standard Masyu rules apply.
0
votes
1answer
84 views

How to solve the attached sudoku?

Please explain the logic. I am not trying to solve it using trial and error or using any software. I am just looking for the next step. This sudoku is from apple 'Sudoku King' app.
2
votes
1answer
161 views

How could I solve the attached Sudoku?

Please explain the logic. I am not trying to solve it using trial and error or using any software. I am just looking for the next step. This sudoku is from apple 'Sudoku King' app.
12
votes
1answer
270 views

9x9 Sudoku Slitherlink Hybrid

I previously created a combined slitherlink and sukoku puzzle, but I was unsatisfied because the grid was smaller then a regular sudoku. So I made another, larger one. Below is a 9 by 9 grid. This is ...
9
votes
1answer
150 views

Sudoku: Episode 64 - Attack of the Clones

An 8x8 Sudoku where you technically only have to figure out 32 cells! Twice Half the cells, double the clues! Penpa Link Rules Normal Sudoku rules apply. Values are 1-8. Boxes are the 4x2 regions ...
17
votes
2answers
591 views

Pipes Puzzle Uniqueness

In the puzzle game Pipes, a space-filling tree of pipes (which may have either one, two, or three neighboring connections each, but not four) is scrambled by a series of tile rotations, and the goal ...
6
votes
1answer
209 views

A 3x3 grid with common factors

A $3 \times 3$ grid $G$ is filled with every number from the set $\{2,3,5,6,7,11,14,15,30\}$. Now a new $3 \times 3$ grid $H$ is formed, such that $H_{ij}$ is the number of neighbors of $G_{ij}$ that ...
11
votes
4answers
944 views

Deriving a 3x3 grid from another one

A $3 \times 3$ grid $G$ is filled with every number from $1$ to $9$. Now a new $3 \times 3$ grid $H$ is formed, such that $H_{ij}$ is the number of neighbors of $G_{ij}$ that are greater than $G_{ij}$....
5
votes
1answer
145 views

Sudoku + Slitherlink

I like combinations of puzzles, so I decided to combine a Sudoku and a Slitherlink. Below is a 6 by 6 grid. This is filled in with numbers based on the usual rules of sudoku. All of the numbers from 1 ...
-1
votes
1answer
120 views

Fillomino: Number Attack!

This is my first time making a Fillomino. Hope you enjoy! Fillomino (taken from Nikoli): Fill in all empty cells with numbers under the following rules. Divide all of the board into blocks. Fill ...
6
votes
1answer
105 views

A Somewhat Foolish Poem

Your task is to solve the Sudoku and complete the missing words in the following poem. Classic Sudoku: Each row column and box contains the digits 1-9. XV-rules: Digits separated by V must add to 5. ...
21
votes
1answer
532 views

Slitherlink: Around the W0rld

Rules of Slitherlink: Connect adjacent dots with vertical or horizontal lines to make a single loop. The numbers indicate how many lines surround it, while empty cells may be surrounded by any number ...
-1
votes
1answer
129 views

Skyscrapers 7x7 How to get next Skyscraper on field

I have the following Skyscrapers puzzle: C3 C1 C2 C3 C4 C4 C2 C2 V3 C5 C4 V1 C1 C3 C4 C2 V5 C3 C3 V7 C3 C3 V4 V2 C2 C1 V2 C2 C1 C3 C4 C2 C2 C2 C2 C -> Clues how many ...
23
votes
1answer
747 views

Polly O'Mino's Hexcellent Adventure

An entry in Fortnightly Topic Challenge #52: Polyominoes. I had heard that my good friend Ingrid Deduction was back in town, so I popped round to her apartment today, only to find she'd got herself a ...
10
votes
3answers
904 views

Calculation Sudoku

Here is a new quiz from my daily quiz calendar. I'm trying to find a way to solve it. The numbers 1-6 should be filled in. And like a sudoku, each row and each column should contain each number ...
18
votes
1answer
390 views

A constrained, but concerning, celestial confrontation

An entry in Fortnightly Topic Challenge #52: Polyominoes. This puzzle is a hybrid between Pentominous and Star Battle. Your job is to divide the grid below into pentominoes according to the rules of ...
1
vote
1answer
114 views

Next Move on this Sudoku Classic

What would be the next move? Link to this sudoku
4
votes
3answers
793 views

Why is the next Sudoku step a 6?

I used a step-by-step Sudoku solver for a puzzle in which I was stuck. However I don't understand how the next number (6) was found. Sudoku puzzle where I was stuck: Sudoku puzzle solved by one step ...
1
vote
1answer
91 views

4-DominoBrane #002 “81”

Here is another domino puzzle. This is considerably easier than puzzle set earlier this week, and definitely doesn’t need bifurcation. This uses 4-Dominoes (all the normal dominoes, minus any with a 5 ...
14
votes
1answer
295 views

Tapa on a Penrose Tiling

An entry in Fortnightly Topic Challenge #51: Non-rectangular grids. This is a standard Tapa puzzle, on a non-standard Tapa grid...the "grid" is a Penrose tiling! Since the grid is not ...
3
votes
1answer
235 views

Slitherlink: The Couple of Question Marks

This is my first slitherlink puzzle. I made it myself. Feedback is appreciated! (I hope this one has a unique solution, unlike my other past puzzles, wink). Rules of Slitherlink (taken from Nikoli): ...
1
vote
1answer
122 views

4-DominoBrane Exclusive

Here is a smaller puzzle from the set of domino puzzles, I call DominoBrane. This uses 4-Dominoes (all the normal dominoes, minus any with a 5 or a 6). Each domino ...
4
votes
1answer
156 views

DominoBrane - Chained Domino Fitting

So I've been working on a set of domino puzzles, I call DominoBrane recently, it's sort of similar to Dominosa - except that, unlike Dominosa, the rules of the ...
15
votes
1answer
317 views

Haisu: Schezo's Birthday

Rules of Haisu: Draw a path from S to G passing through all white cells exactly once by connecting the centres of adjacent cells. When the path passes over a number N, it is on its N-th entry to the ...
10
votes
1answer
298 views

The Nurikabe of Peace

Today is the 75th anniversary of Sir Winston Churchill's speech "The Sinews of Peace" which introduced to the world the phrase "The Iron Curtain". This puzzle is inspired by that ...
8
votes
2answers
224 views

Double sudoku - two-digit numbers, the 1s and 10s places both form Sudokus [closed]

Using distinct 2-digit numbers from 11-99 that have no zeros, fill in the grid so that the tens digits form a Sudoku and the units digits form a (different) Sudoku. There might be a mathematical way ...
19
votes
1answer
435 views

Escape from Sudoku!

An entry in Fortnightly Topic Challenge #50: Escape Rooms I hesitated to enter this in the Escape Room FTC, but I definitely was inspired by the challenge to create this puzzle, and it is, in some ...
11
votes
1answer
454 views

The Puzzling Free-to-Play Escape Room, naturally!

An entry in Fortnightly Topic Challenge #50: Escape Rooms Without revealing too much, knowledge of geek culture and/or superb Google skills are required for this puzzle. Coming from an anime ...
1
vote
4answers
156 views

I need some help with this 15x15 nonogram

I have been working on this nonogram for some time and can't seen to figure out what to do next... This is the link: https://nonograms-katana.com/play/#game
8
votes
1answer
224 views

Nurikabe: The Terrible Tower of Threes!

This puzzle is a quick and fun little Nurikabe that is very tall, because I am not. It's not particularly tough, but if you need a nice relaxing grid-deduction puzzle to calm your brain today, this ...
1
vote
1answer
124 views

Number crossword puzzle

I'm trying to solve the following quiz from my daily quiz calendar (I have it in paper so I cannot give a link). It's like a crossword puzzle but with numbers. The empty cells should be filled with ...
6
votes
1answer
198 views

Fillomino with Sums: The Fillo That Smiles Back!

This puzzle is a Fillomino, with the special variant rule of Sums ("Cages") being applied. You might also notice that this particular fillomino is giving you a smile! This is my first time ...
9
votes
1answer
394 views

Trivia… sudoku

An entry in Fortnightly Topic Challenge #49: Pub Quiz Camouflage Please do not search the answers online (hence the no-computers tag), otherwise it would be too simple to solve this puzzle. I tried ...
5
votes
1answer
199 views

Double Ducky (or Fu-two-shiki)

There are two* logical, discrete ways to solve this Futoshiki puzzle, each with its own unique solution. You can solve it using the letters given, or use the numbers 1-5, but if you map the letters to ...
0
votes
1answer
102 views

Skyscraper 6x6 - unable to get next step

I tried to write a program to solve a Skyscrapers puzzle. Currently I'm teaching it to find the next steps out of nopes (values which cannot be present on the field) values and clues. So far the field ...
9
votes
1answer
177 views

Scrabblescrapers

An entry in Fortnightly Topic Challenge #48: Unusual tag mix In this puzzle, you are given a 5x5 grid that you need to populate with a word square, so that the rows and columns form words (as defined ...
14
votes
2answers
611 views

Now you're Packing with Portals #2: Hashtag

Place the colored shapes into the white area, without rotations or reflections, so that they fill it perfectly. The gray walls don't just block shapes, though - they act as portals! When you place a ...

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