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.

Filter by
Sorted by
Tagged with
2
votes
0answers
51 views

Mega-puzzle of many number puzzles: Nikoli Octathlon

This puzzle has been my Moby Dick of puzzles for so long. It's from MellowMelon's old puzzle site and is a Nikoli-based megapuzzle with eight sub-puzzles. I'm copying the puzzle image from there so as ...
13
votes
1answer
256 views

Sub Battle Sudoku

Please find below a variant Sudoku which incorporates elements of Star Battle. The Sudoku is a standard irregular Sudoku, and the clues outside the grid are sandwich clues: the sum of digits strictly ...
15
votes
1answer
334 views

Sum-until-1 Fillomino: Odds, Fibonacci, and Pi

Fillomino rules (taken from Nikoli): 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 ...
25
votes
2answers
1k views

Encrypted Snake (Grid Puzzle)

Rules of Snake: Shade some cells to form a non-intersecting path which does not touch itself, not even diagonally. Black circles must lie on one end of the path. White circles must lie somewhere ...
8
votes
1answer
426 views

Where's the path?

A person was shading several unit squares in a square grid, to create a path from the bottom left corner to the top right corner. The path stepped from each square to the next either horizontally or ...
13
votes
1answer
253 views

Mid-loop: Coming Soon

Rules of Mid-loop: Draw a single loop passing through all of the black dots. The loop may not branch off, intersect, or move diagonally. The loop cannot bend at the black dot. Each black dots denotes ...
12
votes
3answers
870 views

Masyu puzzles with many circles

The rules of Masyu: 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 cell twice. ...
14
votes
3answers
305 views

Cross ALL the Streams

This grid deduction puzzle is a hybrid of three puzzle types: Cross the Streams, Tapa and Star Battle; rules for each are summarized below. In this grid, every cell is to be shaded either red, blue, ...
9
votes
2answers
310 views

Trio Tapa: Introduction

Rules of Tapa (copied from here): Shade some cells of the grid. Shaded cells should form a single [orthogonally] connected group; no 2×2 square should be fully shaded. Some cells have clues in them. ...
17
votes
2answers
654 views

XV Sawtooth Sudoku

Please find below a variant Sudoku puzzle, based on a combinatorics problem I was having a look at. The timing is right, as I recently saw @BeastlyGerbil back in chat, and I know that user is a big ...
2
votes
1answer
584 views

A tough Word-Nurikabe puzzle

I came up with this Word Nurikabe Puzzle, which was NOT a part of the Puzzle Ramayan, the qualifiers for Indian Puzzle Championship. Rules Place the given words in the grids ‘islands’, so ...
2
votes
2answers
201 views

How to get started on this Slitherlink (No Swiss)?

This is a puzzle from Round 4 of WPF's Puzzle Grand Prix this year. It's a Slitherlink with the additional rule that "Every Swiss cross-shaped arrangement of five cells must contain at least one ...
-10
votes
0answers
120 views

MATHEMETICS GRADE 5 QUESTION DIFFICULTY LEVEL TOUGH

In a 3x3 grid, I'd have to put numbers from 1 to 9 in a manner so that respective row, column and diagonal add up to 14
7
votes
1answer
226 views

Toroidal Weaved Truncated Square Tiling Tapa

Rules of Toroidal Weaved Truncated Square Tiling Tapa: The grid wraps around horizontally and vertically and also is divided into several 1-cell and 3-cells tiles. Shade some tiles such that all ...
1
vote
1answer
241 views

Can Arrows puzzles have multiple solutions?

I am trying to make an Arrows puzzle, but I don't know if there are multiple solutions. For those who don't know, an Arrows puzzle starts with a grid of numbers (example from SE) surrounded by empty ...
3
votes
1answer
677 views

What's the next step for this Kakuro puzzle?

What's the next step for the below Kakuro puzzle? Source: Puzzle Page app
10
votes
1answer
173 views

3D Tapa - Count to Five

Rules of 3D Tapa: The grid is a 3-dimensional cubes, represented here by layers of cubes from top to bottom. Shade some cubes such that all shaded cubes form a single orthogonally (in 3-axis) ...
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 ...
5
votes
1answer
468 views

The next steps for this Kakuro puzzle

What are the next steps for this Kakuro? I've solved most of it, but there is an area I'm stuck on. Source: Puzzle Page app
7
votes
1answer
306 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
461 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
286 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 ...
4
votes
5answers
508 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
305 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 ...
3
votes
5answers
822 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
718 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
349 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
389 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
727 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
247 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
510 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
196 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
472 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
281 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
851 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
239 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
3k 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
180 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
926 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
562 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
390 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
292 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
222 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
322 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
883 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
453 views

Windmill: A Masyu Puzzle

The standard Masyu rules apply.
0
votes
1answer
96 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.

1
2 3 4 5
15