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.
1,141 questions
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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 ...
- 17.1k
13
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2
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245
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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 ...
- 17.1k
3
votes
1
answer
252
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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 ...
- 2,857
6
votes
1
answer
217
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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, ...
- 17.1k
9
votes
2
answers
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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 ...
- 173
11
votes
3
answers
682
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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 ...
- 17.1k
4
votes
1
answer
257
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Minimally clued 5x5 Hidato
Puzzle attribution: Me
Goal of Hidato:
Fill in a grid with a series of consecutive numbers that connect each other orthogonally or diagonally
To get the green checkmark $\color{green}✓$:
Solve the ...
- 2,857
-4
votes
1
answer
128
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Binary Grid Challenge and X & O Conundrum
You are given a 5x5 grid with some cells filled with either "X" or "O". Your goal is to fill the remaining cells with "X" or "O" following these rules:
Each row ...
- 109
13
votes
3
answers
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What is the minimum amount of numbers needed to create a 4x4 Hidato with a unique solution?
Goal of Hidato:
Fill in a grid with a series of consecutive numbers that connect each other horizontally, vertically, or diagonally.
So I have been working on figuring out the minimum number of ...
- 2,857
5
votes
1
answer
623
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Is the 7-clue 6x6 Sudoku solvable?
So I was trying to find an 8-clue 6x6 Sudoku because I knew from this paper that only 8 clues were needed to create a 6x6 Sudoku with a unique solution.
However, I have managed to find one with 7 ...
- 2,857
23
votes
1
answer
918
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Invalid Jigsaw Sudoku Layout
The Jigsaw Sudoku Layout below is invalid (no Latin Squares exist for it). Why?
Please find a short, yet complete, explanation (no computations involved).
...
- 470
9
votes
1
answer
522
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Light Up (Akari), but on a real projective plane!
This is a Light Up (aka Akari) puzzle, except it is on what is called a real projective plane. A real projective plane is, simply put, just a Möbius strip with a single edge except for the fact that ...
- 2,857
19
votes
2
answers
773
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An unusually tricky Galaxy
Background
I love Simon Tatham's Puzzles, especially for killing the odd few minutes. One of the available puzzles is Galaxies, based on Tentai Show. I can usually solve these in anywhere from 30 ...
- 397
7
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1
answer
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An Irregular Colombian Sudoku
Solve the Irregular Sudoku below (by Xavier Castillo), where 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 ...
- 19.2k
19
votes
1
answer
1k
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Mercury in Centigrade
This is part 55 of the puzzle series Around the World in Many Days. Each part is solvable on its own.
Dear Puzzling,
This is a non-consecutive thermo sudoku. Fill the grid so that each row, column ...
- 81.1k
2
votes
1
answer
223
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What can I deduce next about this daily Light Up (Akari) puzzle? (Feb. 22, 2024, 7x7 Hard)
So yesterday, I was searching for online logical deduction puzzles when I came across this website called Brain Bashers which is a site filled with many different types of puzzles.
I have been going ...
- 2,857
2
votes
2
answers
204
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What can I next logically deduce in Day 62 of the Minesweeper Advent Calendar? (Fake 3D)
So I have gotten back into playing the Minesweeper Advent Calendars on heptaveegesimal.com, and recently came across the 2023 Minesweeper Advent Calendar. I am currently trying to beat Day 62, which I ...
- 2,857
13
votes
1
answer
2k
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Add rules to Minesweeper until you can start with nothing
Think of classic Minesweeper game, with the following list of restrictions on the placement of mines:
C (Connected): All mines are connected via 8-way neighborhood (orthogonal and diagonal).
Q (Quad):...
- 17.1k
5
votes
1
answer
236
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The Minesweeper Puzzle That Might Stump People
I thought this might be a different kind of puzzle. This is a game of Minesweeper that I played earlier today.
All standard rules apply. For those who don't know, the number inside of each cell ...
- 554
3
votes
1
answer
239
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Impossible pattern in slitherlink
The puzzle here is to analyze the following Slitherlink configuration and show that it is impossible.
...
- 470
7
votes
3
answers
1k
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Continue a hard Loopy/Slitherlink puzzle without brute-force
This is a classic Slitherlink puzzle from Simon Tatham's Portable Puzzle puzzle collection. I was stuck at the position shown for quite a while until I found a way to continue by logical deduction. I ...
- 2,264
9
votes
2
answers
521
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Unchained Again
This is part 53 of the puzzle series Around the World in Many Days. Each part is solvable on its own.
Dear Puzzling,
The black and white circles in this grid form a Masyu puzzle. Draw one continues ...
- 81.1k
7
votes
2
answers
562
views
A Colombian Jigsaw Sudoku
This is a Colombian Jigsaw Sudoku where the usual rules apply, but with irregular boxes. The dots in the right-hand scheme indicate how many of the numbers in a particular row or column are correctly ...
- 2,155
2
votes
1
answer
188
views
How do I transcribe a Kakuro into a Google Sheets?
As other questions of mine mentioned, I have been slowly working through some PDF puzzle books. I will shortly come up on Kakuro puzzles. Here is an example from the Wikipedia article:
The parts ...
- 10.6k
4
votes
1
answer
292
views
27 Directional Lights Celebrate 2024
Let us celebrate the start of 2024! (1 month late...)
Direct each light (yellow) such that all unlit squares (white) are lit. Walls (black) block light from going through.
Some clarifications of the ...
- 3,223
11
votes
1
answer
596
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One more Colombian Sudoku
Here is one more Colombia Sudoku devised by Xavier Castillo. The usual sudoku rules apply.
The dots outside the board above indicate how many cells in the corresponding column or row of that board ...
- 19.2k
4
votes
1
answer
391
views
Creeper Lighting
There are two sets of similar but separate puzzles here; the white puzzle (with white cells) and the black puzzle (with black cells). Each puzzle is solved independently.
Each number is a "...
- 3,223
9
votes
1
answer
616
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Hardcore Lighting - Excalidraw
Each yellow cell is a light that shines in exactly one direction, horizontally, vertically, or diagonally, endlessly, and goes through any block as long as the block is not a wall. Black cells do not ...
- 3,223
16
votes
1
answer
777
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Nurikabe: Back to basics
Rules of Nurikabe: Shade some cells in the grid. Each area of unshaded cells must contain exactly one number, which indicates the size of that area. Two unshaded areas may not share an edge, but they ...
- 81.1k
-1
votes
1
answer
193
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Minesweeper Queens
Based off of: Ken Duisenberg's Puzzle of the Week Oct. 15, 2003: Minesweeper Queens
For the puzzle, in the given diagram, the numbered squares are empty, from which the given mines can be attacked by ...
- 2,857
12
votes
1
answer
539
views
Aquatic Giants – Heyawake / Marching Bands
This is part 52 of the puzzle series Around the World in Many Days. Each part is solvable on its own.
“One, two, three, four, five, I love marine wildlife.” – unknown
Dear Puzzling,
The grid on the ...
- 81.1k
1
vote
1
answer
289
views
What‘s the next step to solve this 10x10 nonogram?
I got stuck on this nonogram (picross) from the game “Murder by Numbers”:
What is the next step from here?
- 835
2
votes
2
answers
832
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On solving the minimally clued 8x8 Sudoku
So I have been doing research on the minimal amount of numbers needed to create an 8x8, and found this paper which went over the minimum amount of clues needed for a sudoku to have a unique solution ...
- 2,857
27
votes
1
answer
2k
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Orange on Turquoise
This is part 50 of the puzzle series Around the World in Many Days. Each part is solvable on its own.
Dear Puzzling,
This is a Beaches puzzle (or tricolour Aquariums, if you prefer). Shade some cells ...
- 81.1k
12
votes
2
answers
561
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sums and differences in consecutive grid [closed]
Fill in each square of the grid with a number from $1$ to $16$,
using each number exactly once. Numbers at the left or top give
the largest sum of two numbers in that row or column. Numbers
at the ...
- 589
14
votes
1
answer
322
views
! ! ! HNY 2024 ! !?
The following puzzle is a typical Sudoku 12 x 12 (1-9, a, b, c), but with an added twist. In addition to the standard rules, each colored box must also contain unique digits; no repetition is allowed ...
- 2,155
3
votes
1
answer
115
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Help with nearly finished expert sudoku
I just started with Sudoku and I jumped directly to a difficult level.
I have a hint but don't want to use it. Please provide logic with your answer.
- 31
13
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1
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Happy and joyful 2024!
Fill each empty cell of the board on the left with a digit between 1 and 9. Each box and each column and row must contain all digits.
The dots outside the board on the right indicate how many cells in ...
- 2,155
12
votes
1
answer
383
views
Towering Above – a jigsaw crossword
This is part 49 of the puzzle series Around the World in Many Days. Each part is solvable on its own.
Dear Puzzling,
This is a jigsaw crossword. Fill every row and column of the grid using the given ...
- 81.1k
0
votes
0
answers
105
views
Heuristic function for estimating nurikabe puzzle state
I am trying to write a program for solving nurikabe puzzle. I need a method to approximately represent the state of the game in one number, to choose the best way for the algorithm to continue. I can'...
- 1
17
votes
1
answer
684
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Wreck Exploration
This is part 48 of the puzzle series Around the World in Many Days. Each part is solvable on its own.
Dear Puzzling,
The larger grid here is a Takuzu puzzle (also known as Binairo). Fill the grid ...
- 81.1k
14
votes
2
answers
908
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PSE Advent Calendar 2023 (Day 20): Candles on the tree
This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2023. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door >
Rules of ...
- 81.1k
1
vote
1
answer
114
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How do I do the Hard mode version of the 2nd bonus puzzle unlocked after beating level 45 in Hexologic?
In Hexologic, there are bonus levels that you can unlock after completing each 15 levels. (although it doesn't matter if it's on Easy or Hard mode) I have been able to complete all of the bonus levels ...
- 2,857
6
votes
1
answer
564
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PSE Advent Calendar 2023 (Day 18): A holly jolly Hexologic
This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2023. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door >
Rules:
...
- 2,857
3
votes
3
answers
859
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How to solve Level 45 in Hexologic (easy mode)
For those who don't know how Hexologic works:
You can place one, two or three dots in each blank space and the rows that end in arrows must all add up to the number in the arrow.
Here is Level 45 (...
- 2,857
11
votes
1
answer
496
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Best Wishes for 2024: Four empty Suguru (Tectonic) puzzles
To continue last year's tradition, hereby four empty suguru puzzles.
Rules of suguru: Each square gets a number so that each block of n squares has the numbers 1..n, and neighbouring squares (...
- 1,445
18
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1
answer
865
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PSE Advent Calendar 2023 (Day 11): Divide the cookies and milk
This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2023. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door >
Santa’s ...
- 81.1k
16
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2
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515
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Another type of Sudoku puzzle
I just found a weird-looking sudoku I left years ago in my basement:
I think there was a specific name for this type of puzzle, but I forgot to write it down and now I can't remember it!
The only ...
- 5,105
18
votes
2
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811
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PSE Advent Calendar 2023 (Day 9): The Peppermint Twist
This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2023. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door >
This puzzle ...
- 29.2k
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3
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What technique can be used to solve this 6x6 sudoku?
Which Sudoku technique can be used to solve this? The screenshot is from the open source Sudoku app by SECUSO (Security Usability Society) for the Android platform.
