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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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 ...
Matthew's user avatar
  • 287
7 votes
1 answer
180 views

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 ...
Bernardo Recamán Santos's user avatar
16 votes
1 answer
764 views

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 ...
Jafe's user avatar
  • 77.7k
2 votes
1 answer
92 views

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 ...
CrSb0001's user avatar
  • 1,622
2 votes
2 answers
152 views

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 ...
CrSb0001's user avatar
  • 1,622
12 votes
1 answer
2k views

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):...
Bubbler's user avatar
  • 12.2k
5 votes
1 answer
185 views

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 ...
Truej's user avatar
  • 522
3 votes
1 answer
191 views

Impossible pattern in slitherlink

The puzzle here is to analyze the following Slitherlink configuration and show that it is impossible. ...
JCO's user avatar
  • 138
7 votes
3 answers
1k views

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 ...
quarague's user avatar
  • 1,841
9 votes
2 answers
415 views

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 ...
Jafe's user avatar
  • 77.7k
7 votes
2 answers
462 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 ...
Xavier Castillo's user avatar
3 votes
1 answer
137 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 ...
bobble's user avatar
  • 10.2k
4 votes
1 answer
279 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 ...
Sny Smartie's user avatar
  • 2,264
11 votes
1 answer
405 views

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 ...
Bernardo Recamán Santos's user avatar
4 votes
1 answer
366 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 "...
Sny Smartie's user avatar
  • 2,264
9 votes
1 answer
588 views

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 ...
Sny Smartie's user avatar
  • 2,264
16 votes
1 answer
728 views

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 ...
Jafe's user avatar
  • 77.7k
-1 votes
1 answer
151 views

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 ...
CrSb0001's user avatar
  • 1,622
12 votes
1 answer
467 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 ...
Jafe's user avatar
  • 77.7k
1 vote
1 answer
252 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?
hb20007's user avatar
  • 845
2 votes
2 answers
722 views

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 ...
CrSb0001's user avatar
  • 1,622
26 votes
1 answer
1k views

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 ...
Jafe's user avatar
  • 77.7k
12 votes
2 answers
521 views

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 ...
godlification's user avatar
14 votes
1 answer
266 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 ...
Xavier Castillo's user avatar
3 votes
1 answer
88 views

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.
Steve's user avatar
  • 31
13 votes
1 answer
467 views

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 ...
Xavier Castillo's user avatar
11 votes
1 answer
324 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 ...
Jafe's user avatar
  • 77.7k
0 votes
0 answers
73 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'...
Papouc's user avatar
  • 1
17 votes
1 answer
620 views

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 ...
Jafe's user avatar
  • 77.7k
14 votes
2 answers
857 views

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 ...
Jafe's user avatar
  • 77.7k
1 vote
1 answer
94 views

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 ...
CrSb0001's user avatar
  • 1,622
6 votes
1 answer
519 views

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: ...
CrSb0001's user avatar
  • 1,622
3 votes
3 answers
820 views

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 (...
CrSb0001's user avatar
  • 1,622
18 votes
1 answer
814 views

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 ...
Jafe's user avatar
  • 77.7k
16 votes
2 answers
462 views

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 ...
Jujustum's user avatar
  • 3,505
18 votes
2 answers
762 views

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 ...
Jeremy Dover's user avatar
  • 27.4k
8 votes
3 answers
1k views

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.
Rajesh Krishnaiah's user avatar
21 votes
1 answer
1k views

PSE Advent Calendar 2023 (Day 3): 24 dangerous doors

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 > Task: Solve ...
Lukas Rotter's user avatar
  • 10.3k
1 vote
1 answer
104 views

What is the next logical step I can take when solving the Nov. 30 2023 Sudoku in the Wisconsin State Journal?

Note: sorry for posting this on Dec. 1, but don't worry, I haven't looked at the Sudoku solution yet. So today I decided to try to solve the Sudoku in the Wisconsin State Journal. Now, even though ...
CrSb0001's user avatar
  • 1,622
11 votes
2 answers
677 views

Turn Back the Clocks

This is part 45 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a Slitherlink puzzle. Draw a single continuous loop along grid lines that ...
Jafe's user avatar
  • 77.7k
-1 votes
1 answer
120 views

Is the "Challenging" Kenken in the Wisconsin State Journal from April 27 2021 solvable?

Note: The reason that I picked this one to self-answer was because it was a few weeks (months?) before the Wisconsin State Journal stopped printing Kenken puzzles. This was also the newest Kenken from ...
CrSb0001's user avatar
  • 1,622
1 vote
1 answer
121 views

Filling in an 8x8 minesweeper grid with mines (Day 11: Christmas tree edition)

Previous puzzles Contains: Single mines (1 mine), Double mines (2 mines), Triple mines (3 mines) To get the $\color{green}✓$: Solve the Nonogram Solve the Minesweeper puzzle Note: partial answers ...
CrSb0001's user avatar
  • 1,622
1 vote
1 answer
81 views

Sudoku variants #2: Lined Numbers (6x6 grid)

Previous variant Today's Sudoku variant is a bit weird. Here's why: Take this screenshot: From this, you might argue that there is nothing that can be logically deduced on this grid. Now you might ...
CrSb0001's user avatar
  • 1,622
2 votes
1 answer
160 views

Filling in an 8x8 minesweeper grid with mines (Day 10: Double Neighbors)

Previous Minesweeper puzzles Based off of Day 10 of the Minesweeper Advent Calendar on heptaveegesimal.com Difficulty (approximate): ★★★★☆ Contains: Single mines (1 mine), Anti-mines (-1 mines), ...
CrSb0001's user avatar
  • 1,622
5 votes
1 answer
265 views

Another puzzle combination (feat. Kakuro)

Today, I am going to give you another puzzle combination. This time, it features a Kakuro! However, there are some things to note: There are only two puzzles that I have combined, although you have ...
CrSb0001's user avatar
  • 1,622
4 votes
1 answer
124 views

A Hokuro, but with a twist!

Recently, I created my first Hokuro puzzle, which was received really well. However, this time, there is a twist! Not with the rules or anything, however, it is combined with a Nonogram! Luckily, the ...
CrSb0001's user avatar
  • 1,622
1 vote
1 answer
194 views

A 6x6 table with nothing filled out?

So as you might or might not know, I can be quite evil sometimes, especially with my Hidato puzzles that contain no numbers. But, today, I decided to give you an enigmatic-puzzle! This means that you ...
CrSb0001's user avatar
  • 1,622
-1 votes
1 answer
124 views

Anyone up for a 3x3x3 Hidato?

So, I have been pretty evil with how I make Hidato puzzles lately, with there being no numbers. To make up for it, I have decided to make a 3x3x3 Hidato for you all. Yes you read that right. I made a ...
CrSb0001's user avatar
  • 1,622
1 vote
1 answer
173 views

How would I be able to solve this difficult Hidato?

So I was doing Hidato puzzles on the official Hidato site when I came across this puzzle that I am having trouble solving, and while I have been able to solve it partly, I don't think that I'm going ...
CrSb0001's user avatar
  • 1,622
2 votes
1 answer
139 views

A Hidato, but with no given numbers? #2: 5x5

Previous puzzle As you may or may not know, I can be a bit evil sometimes. Today, I am going to give you a 5x5 Hidato with no given numbers to start. However, this isn't a Mobius Strip puzzle like ...
CrSb0001's user avatar
  • 1,622

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