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 ...
4
votes
1answer
282 views

A slightly different type of Sudoku puzzle

The following image shows two valid Sudokus. The first was copied verbatim off Wikipedia, and the second was obtained by rotating 90 degrees. Any two distinct valid Sudokus must differ in at least ...
5
votes
6answers
505 views

Good resource for daily Sudoku Puzzles [closed]

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 book below. Mastering ...
5
votes
1answer
301 views

Nurikolor (Level 1)

Next level: Nurikolor (Level 2) Welcome to my new puzzle: the NURIKOLOR, which is essentially the colored version of Nurikabe, but not exactly, with a few twists. The rules are simple: There are ...
8
votes
1answer
1k views

Is there another name for this puzzle? (Kyudoku, Nine Find)

Is there another name for this type of puzzle? I can only find two examples of it online: https://www.brainzilla.com/logic/kyudoku/ http://ninefind.com/ In the game you start with a 6x6 grid filled ...
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?
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 ...
-2
votes
7answers
18k views

2x2 row and column equations

Rules: No paper or notes, but a calculator is accepted. Post the exact time min wise of how long it took. And obviously give the answer.
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 ...
6
votes
1answer
371 views

How to solve this Loopy puzzle efficiently with little backtracking?

I would like to solve this Loopy (Cairo) puzzle: But I would like to do so with as little backtracking as possible. By this I mean that I want to have at most one pending guess at a time; I do not ...
10
votes
2answers
720 views

Can you solve this Masyu puzzle?

Hey guys, enjoy this Masyu puzzle! For those unfamiliar with Masyu, here are some instructions: The goal of Masyu is to connect the circles on the grid via a line that closes itself and also does not ...
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 ...
11
votes
2answers
506 views

Mosaic by Albrecht Dürer

This is a visual puzzle (known as "mosaic" or "fill-a-pix") with the same rules as MineSweeper: The grid is to be filled with colored and white tessera. Choose whatever color you like for the colored ...
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 ...
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 ...
4
votes
2answers
279 views

Why are 2s not possible in these Sudoku cells?

I recently was playing Sudoku on my iPad. As I was stuck on the puzzle I clicked on "Tip" to receive a hint on how I can solve this Sudoku (I am still learning the game) - so please don't ...
4
votes
2answers
2k views

Are there any sudoku puzzles combined with magic squares? [duplicate]

As everyone knows, in Sudoku the sum of each row and column is 45. So all Sudoku solutions are some kind of magic square. My question is: Has anyone seen a Sudoku puzzle combined with the magic square ...
7
votes
1answer
843 views

What is the fewest number of clues on a rotationally symmetrical sudoku grid with a unique solution?

It is known that the minimum number of clues a sudoku must have to have a unique solution is 17. But on every website I've seen for them, I haven't found any that are rotationally symmetrical. I once ...
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 ...
9
votes
1answer
2k views

A Sudoku with only four given digits and some more rules

This is one of the hardest Sudokus (and one of the best Sudokus) I have ever seen, with only 4 given digits. There are some more rules too: First, normal Sudoku rules apply here. Both the diagonals ...
2
votes
2answers
175 views

Next step/strategies for an Area 51 (Slitherlink variant) puzzle

I've been doing quite a few Slitherlinks recently (and puzzles containing Slitherlink elements, such as Area 51). I'm familiar with all the patterns described in the Wiki article but I feel like there'...
10
votes
2answers
924 views

13-by-13 SIKAKU puzzle

A SIKAKU puzzle consists of a square or rectangular grid in which some of the cells contain a one or two digit number. To complete the puzzle, a Solver must divide the puzzle into a number of ...
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 ...
4
votes
1answer
377 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?
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 ...
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 ...
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 ...
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 ...
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.
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. ...
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 ...
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 ...
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 ...
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 ...
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
2answers
1k views

A new puzzle - Sudoku X V

If someone is able to find the solution... I found 2,3,8 on line 5, column 3-4-5, but after that I am blocked, it looks too difficult for me.
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 ...
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 ...
9
votes
2answers
627 views

I'm Bad at Naming Things, so Just Try to Solve this Patterned Masyu Puzzle!

The original Masyu rules apply. Make a single loop with lines passing through the centers of cells, horizontally or vertically. The loop never crosses itself, branches off, or goes through the same ...
14
votes
2answers
664 views

Distance Puzzle

The rules are: 1. Draw two circles (O) in the empty cells in every row and column. 2. The numbers in the black cells indicate the space between the 2 circles in the black cells' row or column, in ...
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

1
2 3 4 5
14