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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. 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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Question 16 Ripple Effect

This is a Ripple Effect puzzle. The rules of this puzzle are: Fill in each region with numbers from 1 to n, where n is the region size. For instance, the top left region must have the numbers 1 to 5 ...
16
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1answer
558 views

Barrel - Part 1

An entry in Fortnightly Topic Challenge #35: Restricted Title 1. Title based on the very first xkcd. Continued in Barrel - Part 2, Barrel - Part 3, Barrel - Part 4, and Barrel - Part 5. You manage a ...
75
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2answers
3k views
+50

My God, it's full of stars!

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids My dear friend, unknown to us, may have relocated again. He sent me imagery and constellation maps indicating that a distant red ...
52
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4answers
2k views

Desert Irrigation Project

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids My dear friend researches and designs canal irrigation systems in a remote desert. He's been missing for two weeks. Members of ...
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4answers
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WITLESS - A Puzzling Journey

IMPORTANT! READ ME: The only 'puzzle' parts of this are the links, titled 'Set X', 'Inscription X', or 'Constellation X'. Everything else is flavortext, apart from this readme section, although the ...
8
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1answer
197 views

Unusual Sudoku Puzzle

Find the solution to this Sudoku puzzle. The only problem is there aren't any normal Sudoku clues. Instead there are only some cryptic clues. What is the solution and how does the puzzle work? Edit: ...
11
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1answer
685 views

Strategy for solving 0hh1 and Unruly?

Q42's game 0hh1 and Simon Tatham's game Unruly are two almost identical logical deduction games. In each one, we're given a square grid which is to be filled by tiles of two colours, and a certain ...
5
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1answer
188 views

Is ambiguity prevention sufficient reason to infer a clue?

I decided to work my way through Simon Tatham's puzzle collection to broaden my puzzling skills, and have reached the game Dominosa I have a subboard below, where I've eliminated the possibility of 9/...
69
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1answer
2k views

Empty sudoku puzzle

The rules are the same as for a normal sudoku puzzle. The only thing different is that instead of numbers for clues, you have greater than/less than (> <) signs between the cells. Have fun solving!...
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2answers
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I am an island (ysaujdiolkiun)

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids I received an envelope containing two drawings and no return address. I would recognize that handwriting anywhere - my dear friend ...
47
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1answer
2k views

The Ludicrous Loop: over a thousand cells of circular logic!

Flavourtext is for flavour only. Ladies and Gentlemen, are you feeling ludicrous today? A little loopy, perhaps? Then come one, come all, for I have just the thing for you. Lampreys and Jellyfish, ...
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2answers
766 views

Slightly Odd Sudoku

Someone I find very trustworthy continues to insist that this is a valid Sudoku board. It's been a while since I've played, but surely there's a couple of things off here, right? Alright, so that ...
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1answer
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Introducing: Number Slope™

Number Slope™1 is an original2 grid deduction puzzle similar to Sudoku. It is solved on an n-by-n grid, tiled with n n-ominoes. The rules are: Each number from 1 to n must occur once and only once in ...
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1answer
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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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3answers
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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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2answers
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My Uncle's Music Box

Unfortunately, my favorite uncle just passed away. He's the one that taught me all about puzzling, and supposedly found Davey Jones' treasure in his youth. I miss him very much, however, I just ...
15
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2answers
626 views

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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3answers
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Coloring a 4 by 4 grid

I made this simple puzzle a couple of years ago. There are three colors which appear in every row and every column. Moreover, every color appears 5 or 6 times in total. Find the color of the square ...
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2answers
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HAISU (Room Count): An original grid-logic challenge

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
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2answers
2k views

Who can spot the difference?

My family and I have just moved house! Lucky us! So what did my family do? We held a housewarming party, and rung everyone in the neighbourhood up to invite them. So, anyway, people were coming in ...
9
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2answers
705 views

How will you save Mike?

A direct hint: this question. Question starts from here: You are Dr. Nathaniel - a renowned archaeologist, and involved in a research about an ancient site. But, there is only one problem - the ...
27
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1answer
795 views

Every Fourth Wormhole

An entry in Fortnightly Topic Challenge #33: Surface Geometry Mazes
17
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1answer
1k views

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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3answers
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A “Letter” Slope puzzle?

Your brother has been forcing you to some read some of his frankly ridiculous poetry, so, knowing that he was never a numbers man, you decide to vex him with a Number Slope puzzle. In fact, you are so ...
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2answers
432 views

Making a grid deduction puzzle

When making a grid-deduction puzzle, what are the strategies in making it? For most grid-deduction puzzles, simply putting numbers/dots/whatever in the grid simply doesn't cut it. However, sometimes ...
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4answers
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Five Slitherlinks

Solve five Slitherlinks, each with a unique solution. Please say a word regarding (or show an image depicting) each solution method.
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Parallelisation

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids Puzzlers, I am presenting a set of six duo-grids! Of course, I need to tell you how they work - you are given a grid. Looking at it,...
27
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3answers
924 views

Oh no, it's another safe!

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids Oh, did I feel proud after solving the last safe... until I was immediately dimension-doored (or something) into this room! Damn ...
21
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1answer
593 views

Snakes on a Plane! 2

An entry in Fortnightly Topic Challenge #35: Restricted Title 1. Inspired by the title of this xkcd comic. Snakes ... on a plane ... again ... This time 2 specimens of a huge unknown type of snakes ...
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2answers
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Three for the price of one

While browsing through your local puzzle store, you see something you can't resist: a box which promises two grid deduction puzzles for the price of one! The vendor explains that the box contains a ...
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4answers
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JonMark Perry's Grid Logic Puzzle

Consider the following puzzle type proposed by JonMark Perry. Start with a square grid of arrows, each one pointing in one of the four cardinal directions. For example: You start at the ...
16
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1answer
763 views

HAISU: Nought and Crosses

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
14
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2answers
483 views

Adderlink: Almost symmetrical

Rules: Hey, this looks like slitherlink! In fact, it is two slitherlinks added together. So both of the two slitherlinks have clues in exactly the same locations as this grid below. Furthermore, a 2 ...
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2answers
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The Peculiar File

So I was browsing through my computer files earlier and I found a file I'd not seen before. I was wondering if you guys could help me figure out what it's about. This is where I found it: This is ...
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4answers
369 views

A “Find the Path” Puzzle

I invented a puzzle, inspired by Simon Tatham's Portable Puzzle Collection. Is there anything that it could improve on? Was it too easy, or was it too hard? Anything I could add? What must I call it? ...
8
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2answers
638 views

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 ...
8
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3answers
518 views

Ambiguous Grids

After six to eight weeks of waiting, your Shmikoli™ Ambiguous Grid Deduction Puzzle Set has finally arrived! You tear into the box only to discover that the instructions are missing. You shouldn't ...
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1answer
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What is a “unique solution” in a Slitherlink puzzle?

In the question Five Slitherlinks, the querent suggests that "each [Slitherlink puzzle has] a complete solution". I'm newly reading about Slitherlinks, but I don't understand what makes a solution "...
7
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1answer
173 views

Latin Square Puzzle - Difficult

Follow on puzzle from the introductory Latin square puzzle post. The rules It’s a Latin square like sudoku, so there must be the numbers 1-9 exactly once in every row and column. Notice that each ...
5
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2answers
652 views

Incomplete Word Rectangle

This is an incomplete word rectangle: When completed, every row will contain a common English word with four letters, and every column will contain a word with five letters. All of these are common ...
5
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2answers
423 views

Simple grid deduction puzzle

I will let you figure the rules of this one yourselves. Here is the empty grid to assist solvers. Here is a text version of the grid: ...
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2answers
440 views

36-length snake in a 6x6 grid

Based on https://brilliant.org/weekly-problems/2017-05-29/advanced/?p=4 We need to fill a 6x6 grid using the numbers 1-36, each cell having a single unique number, such that: Every two consecutive ...
21
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1answer
1k views

Help! Can you get my puzzle back?

Puzzling has a lot of really complicated stuff these days, so I just wanted to post a simple Boggle grid. You know that game, right? You form words by starting from one letter, then taking adjacent ...
13
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2answers
531 views

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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2answers
322 views

The Terrible Twos of Slitherlink

This question is aimed at people who have a really good grasp of standard Slitherlink puzzles. This is a standard, square cell, 10x10 Slitherlink puzzle I designed. It isn't what I would call a "...
9
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2answers
493 views

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 ...
9
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2answers
530 views

Haisu: Pixel Perfect

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
8
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4answers
483 views

The Knights and the Hounds

(With thanks and congratulations to Lee Leon) We rejoin our heroes several days after the events of The Knights' Gift, at the head of a pack of enormous staghounds, 1000 strong. Such a pack ...
8
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1answer
261 views

Puzzles: Meander

I have come up with an interesting type of puzzle based on the mathematical concept of a meander. The concept, of course, is not original to me, but the type of puzzle is, as far as I know. A ...
8
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2answers
341 views

Cryptic Crossword Sudoku

This puzzle is inspired by Matt’s excellent Cryptic Sucrosswordoku. Below is a sudoku as well as some cryptic clues. The clues lack enumeration and are in no particular order. The solutions to the ...