Questions tagged [logical-deduction]

A puzzle that requires formal logical deduction to arrive at the solution. This suggests more than merely reasoning through clues to find an answer (you might want [situation] for that).

Filter by
Sorted by
Tagged with
4
votes
1answer
159 views

Spiral Stumper Series: Ripple Effect

Spiral Stumper Series is a $5$-puzzles series taken from the Final Round of a local (national) contest, KPK, which has been ended recently and authored by me. The theme is spiral and each puzzle is ...
36
votes
10answers
5k views

Knights and Knaves: What does C say?

You are on a fictional island with two types of people: knights who always tell the truth, and knaves, who always lie. Three of the inhabitants - A, B, and C are standing in the garden. A says, "B and ...
5
votes
1answer
190 views

Spiral Stumper Series: Fillomino

Spiral Stumper Series is a $5$-puzzles series taken from the Final Round of a local (national) contest, KPK, which has been ended recently and authored by me. The theme is spiral and each puzzle is ...
1
vote
0answers
81 views

What are my sisters' ages? (With ice cream!) [duplicate]

This is from a book I read as a child. Steve said to his friend Jessica, "I have 3 sisters. The sum of their ages is the same as my age, and the product of their ages is 36. How old are my sisters?"...
2
votes
2answers
135 views

Stuck on a Tapa (variation)

I am stuck on a Tapa puzzle. I have tried solving it a number of times and keep running into the same problems. I am starting to wonder if it is solvable at all. As far as the puzzle itself goes, best ...
4
votes
1answer
119 views

Spiral Stumper Series: Kurodoko

Spiral Stumper Series is a $5$-puzzles series taken from the Final Round of a local (national) contest, KPK, which has been ended recently and authored by me. The theme is spiral and each puzzle is ...
4
votes
2answers
108 views

Spiral Stumper Series: Tilepaint

Spiral Stumper Series is a $5$-puzzles series taken from the Final Round of a local (national) contest, KPK, which has been ended recently and authored by me. The theme is spiral and each puzzle is ...
99
votes
16answers
1.0m views

Two doors with two guards - one lies, one tells the truth

You are a prisoner in a room with 2 doors and 2 guards. One of the doors will guide you to freedom and behind the other is a hangman --you don't know which is which. One of the guards always tells ...
1
vote
0answers
60 views

Survive from death by asking the right question twist [duplicate]

You are at a path and there is two roads splitting from it. The first one is certain death and the other is the way home. You do not know which way is the right way home, but there are two people. ...
5
votes
5answers
382 views

Lost in time and space

You have been working on your plutonium-powered time machine for years, and now you finally succeeded! At least, you thought you did... After extensive testing with sending back and ...
-1
votes
1answer
138 views

2 IQ questions - what is the logic?

I was taking the test in the following link: https://testyourself.psychtests.com/bin/transfer But I am not really sure what is the answer and the logic behind them in the following questions: Do you ...
7
votes
2answers
358 views

Quick Yajilin Puzzles: Scatter and Gather

Yajilin (adapted from Nikoli) Draw a line to make a single loop. Lines pass through the centers of cells, horizontally, vertically, or turning. The loop never crosses itself, branches off, ...
6
votes
1answer
180 views

What's the next step in this Unequal (Futoshiki) puzzle?

I'm currently stuck on this puzzle from Simon Tatham's website (he calls it "Unequal", although the standard name according to Wikipedia is Futoshiki). My progress so far is: I've even tried a few "...
1
vote
0answers
69 views

Biuld a Box up Puzzle game [closed]

I want to build a box up puzzle game. I am struggling to implement this. Can you all suggest some sources or logic to implement it? Thanks in advance.
3
votes
3answers
193 views

Maximal sum in 5x5 Minesweeper

How can you place 8 mines on a 5x5 Minesweeper grid such that the sum of the produced numbers is maximal? Are there multiple solutions? Good luck with this!
5
votes
3answers
1k views

Letter Dice Puzzle

I found a puzzle like this online, so I thought I'd try making my own. There are 4 dice, each with 6 different letters on them, such that 24 of the 26 letters of the English alphabet are represented (...
10
votes
3answers
644 views

What is going on? Paintings too?

Part 1: 2 and a half months ago, an old mansion, people are falling sick for no apparent reason. You, a PI, have been dispatched to go and figure out what is happening. It's a snowy day in the middle ...
4
votes
3answers
153 views

Thirteen Minesweeper mines that make seven 5s

Can you place thirteen mines on a Minesweeper grid such that they create seven 5s? The size of the grid can be arbitrary. The mines may create numbers other than 5s, but those are irrelevant. A ...
17
votes
1answer
458 views

Flying pigs arrive

You’ve built pens for flying pigs. Being, well, flying pigs, they pick their own accommodation in full accordance to their preferences. Can you figure out what creature joined them? Pigs only occupy ...
12
votes
3answers
570 views

Quick Kurodoko Puzzle: Threes and Triples

Kurodoko (taken from Nikoli) Colour cells black according to the following rules. The numbers on the board show the number of white cells from the number to the nearest black cell or to the ...
10
votes
2answers
804 views

Twelve Minesweeper mines that make twelve 4s

Can you place twelve mines on a Minesweeper grid such that they create twelve 4s? The size of the grid can be arbitrary. The mines may create numbers other than 4s, but those are irrelevant. Good ...
3
votes
2answers
292 views

Thirsty men problem [closed]

Currently, I am modeling a problem that I am working on (in distributed systems) as a riddle and I'd like to know your opinions, suggestions and solutions. You can find it here on github. Thirsty men ...
2
votes
1answer
103 views

What number should be in the place of “?”

I'm trying to solve this puzzle. Numbers are at triangle, and I have to solve ?-mark: 5 6 1 7 2 5 ? 7 5 Based on solutions it ...
0
votes
0answers
98 views

7 prisoners, 7 hats [duplicate]

There are many red, orange, yellow, green, blue, indigo and violet hats in the prison. 1 day, 7 pirates were caught and was brought to the prison. They warden said,"I will put a hat on your head ...
6
votes
1answer
140 views

*Playtest feedback request* Puzzle 2

This is the second puzzle in the series I'm working on. It's very different from the first as I tried to do different kinds of puzzles for each of these. In this one, players would have to find each ...
4
votes
2answers
346 views

Find the ages of $3$ children based on information given and constraints

A man has $3$ children. Their ages are $a,b,$ and $c$. The constraints are that the ages add up to some value d and multiply to some value e such that $de=756$. Also, no child is more than $3$ times ...
5
votes
2answers
554 views

Gold, silver and bronze in the balance

Equivalent to finding three heaviest coins in order of weight, on a balance that holds one coin on each side. (Simplified, with some Wikipedia references corrected, from the original puzzle. The ...
46
votes
3answers
3k views

Tiling with T-tetrominos in gravity

The goal is to tile all the white squares using T-tetrominos when there is gravity pulling the tetrominos downwards like regular tetris. The black squares are void and the ground is just below the ...
17
votes
1answer
446 views

Awesomism and its awesome gods

Recently, I dived into a nice religion of Awesomism. It is pantheic, with a lot of difficult relations between gods. Twelve gods of Awesomism are split between four pantheons: Gods of cunning: Liar, ...
3
votes
2answers
181 views

Vacation duration puzzle

I was faced with the problem, that I don't think has a solution. Whether someone can confirm my guesses or prove otherwise. Following problem : Joe and Tony take a vacation at Summer camp. During ...
7
votes
2answers
234 views

Quick Shikaku Puzzle: Stars and Stripes

Shikaku (taken from Nikoli) Divide the grid into rectangles with the numbers in the cells. Each rectangle is to contain exactly one number and it's showing the number of cells in the ...
2
votes
2answers
340 views

Find the missing piece (edit)

I guess that these questions may use different logic independently or not i don't know. I just found one logic that fits only to the first one. *These questions are from the one of high IQ Society ...
2
votes
1answer
193 views

Anyone can do a Riley Riddle

I went through a random word generator until I found a nice one to make a Riley out of: My Prefix can crunch, wash, or rock. And can be found prominent, on those who aren't scared. My Infix ...
4
votes
1answer
155 views

Lucy likes Mystery

Lucy likes Jaipur but not Kerala Lucy likes Corbett National Park but not Periyar National Park Lucy likes Assam but not Telangana What does Lucy like, and why? What doesn't she like and ...
7
votes
1answer
162 views

Quick Nurikabe Puzzle: $4$s

Nurikabe (taken from Nikoli) Fill in the cells with black under the following rules. You cannot fill in cells containing numbers. A number tells the number of continuous (adjacently) white ...
7
votes
3answers
255 views

Quick Ripple Effect Puzzle: $70$ Empty Cells

Ripple Effect (taken from Nikoli) The areas divided by bold lines are called "rooms". Fill in all empty cells with numbers under the following rules. Each room contains consecutive numbers ...
6
votes
4answers
580 views

Simple logic puzzle

We think of an island inhabited by rogues and knights. Rogues are always lying, knights always speak the truth. One day 12 islanders come together among which is at least one knight and at ...
1
vote
1answer
174 views

Which number is the odd-one-out in the above set?

In this number set there is something common between the numbers that makes them up into a pattern. Which one of these numbers break up the hidden pattern?
8
votes
12answers
3k views

Time to call the bluff [closed]

You are located outside of two rooms which have a door between them. Each room has one or more computers whose total power is unknown, so they cannot be reliably used as proof-of-work to compare times,...
5
votes
1answer
495 views

Heyawake - why is this wrong solution

Dear people, Why does this particular android game not accept the solution on the right side? Rules in the app:
10
votes
3answers
1k views

How many days for hunting?

There are $10$ hunters who are planning to go hunting in as a few days as possible. Every single day, they choose a group of people or a person to go for hunting, the rest is resting in the camp area. ...
0
votes
0answers
93 views

Tales of Two Cities (With no Gas Stations in between) [duplicate]

Two cities A and B are 100 miles apart. A person has to travel from one city to the other in his old old car, which can travel only 50 miles with its tank full. Unfortunately, there are no gas ...
1
vote
1answer
167 views

Don't Fail MY Exam [duplicate]

A professor decides the following grading scheme in his class. After the final exam is graded, he keeps all the papers upside down on his table in a random order so that no student can recognise his ...
5
votes
1answer
159 views

Quick Moon-or-Sun Puzzles: 2x1-Dominoes and 1x1-Checkerboards

Moon-or-Sun (adapted from Nikoli) Draw a line to make a single loop. Lines pass through the centers of cells, horizontally, vertically, or turning. The loop never crosses itself, branches ...
7
votes
2answers
306 views

Quick Slitherlink Puzzles: KPK and 123

Slitherlink (taken from Nikoli) 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 ...
9
votes
2answers
331 views

Quick Tilepaint Puzzles: Corridors and Corners

Tilepaint (adapted from Nikoli) The areas enclosed by bold lines are called "Tiles" and color the tiles with the following rules. The cells of a tile must all be colored with black or left ...
20
votes
1answer
1k views

Isometric Heyacrazy - Now In 3D!

This is a Heyacrazy puzzle on an isometric grid. Rules of Heyacrazy: Shade some cells of the grid. Shaded cells cannot be orthogonally adjacent; unshaded cells must be orthogonally connected. ...
7
votes
1answer
226 views

A Game of Sprouts

I have a partially played game of sprouts that I need help solving. The rules are simple (Kevin over at VSauce2 did a great job explaining it if you don't like reading, though the Yoda voice is a bit ...
7
votes
1answer
178 views

Heyacrazier: Big Three

This is a Heyacrazier puzzle, a variant of Heyacrazy. Rules of Heyacrazy: Shade some cells of the grid. Shaded cells cannot be orthogonally adjacent; unshaded cells must be orthogonally ...
7
votes
1answer
204 views

Lady C gives 11 different numbers one of which is her age to logicians A and B. What is the age of lady C?

Logicians A and B ask lady C her age. Lady C gives 11 different numbers one of which is her age to logicians A and B: 35, 36, 38, 42, 45, 46, 51, 55, 57, 61, 62 Then lady C tells the digit in tens to ...

1
3 4
5
6 7
44