62 votes
Accepted

The total cost of salaries in a company

Here's my solution:
F1Krazy's user avatar
  • 8,058
54 votes
Accepted

Deceptive dice game

You can make arbitrarily large sets of dice with this property. Start with Efron's dice: A: 4, 4, 4, 4, 0, 0 B: 3, 3, 3, 3, 3, 3 C: 6, 6, 2, 2, 2, 2 D: 5, 5, 5, 1, 1, 1 A beats B, B beats C, C ...
f'''s user avatar
  • 33.7k
52 votes
Accepted

Say 100 and win

because:
astralfenix's user avatar
  • 2,847
51 votes
Accepted

How to get a bowl with one liter of water

The volume filled is:
hdsdv's user avatar
  • 5,190
50 votes
Accepted

The Dwarves' Test

A dwarf with a red dot will A dwarf with a blue dot will Therefore, on the $N$th day, all dwarves with red dots are present, and all dwarves with blue dots are not.
f'''s user avatar
  • 33.7k
49 votes

Red and Blue in the Chocolate Fountain Room

The prisoners agree that: Each prisoner with a blue nose will: Each prisoner with a red nose will:
humn's user avatar
  • 21.9k
49 votes

√2 without pressing √ on a Scientific Calculator

One possibility, if starting with an operation automatically prepends Ans: Why does this work?
Deusovi's user avatar
  • 146k
48 votes
Accepted

Pirate democracy at its finest

I have a hunch that the answer is Explanation: Continuing this way, we see that
Glorfindel's user avatar
48 votes
Accepted

Is there any easy way to solve this lock puzzle?

There is an easy way to solve it in the minimum number of moves. The reason this works is:
Jaap Scherphuis's user avatar
46 votes
Accepted

Can the Policeman catch the Thief?

Yes, the policeman can catch the thief, although it may take a very long time. In particular, the following strategy works: The policeman starts in the center. First, he makes a counterclockwise loop ...
Milo Brandt's user avatar
  • 7,881
42 votes
Accepted

There are 2,001 doors leading to 2,001 hallways. How quickly can you find the way out?

Let's number the hallways (doors) from $1$ to $2001$ from west to east. One important observation is that: This is because: Now, another important observation is that, if a dead-end room connects ...
athin's user avatar
  • 34.2k
41 votes

Will a greedy algorithm solve Tatham's Flood?

It's definitely not optimal! Here's a counterexample: Start from the white area. Greedy algorithm would make you do all the colours on the top right (5 moves: yellow, green, dark green, blue, dark ...
TheGreatEscaper's user avatar
40 votes

How can one solve a Rubik's cube without relying on guides/algorithms?

There are three techniques that allow you to come up with useful move sequences for solving a cube. Conjugation This is where you already have a move sequence that does one thing and allows you to ...
Jaap Scherphuis's user avatar
40 votes
Accepted

retsubkcolB Spelled Backwards

Solved in 10 moves including "Add a comment" and "Add Comment" buttons at the start and end I was muddling around in the "inspect element" for way too long trying to ...
rhavelka's user avatar
  • 598
40 votes
Accepted

Winning chance in coins game with fixing

GoblinGuide's user avatar
39 votes

Will a greedy algorithm solve Tatham's Flood?

That problem is NP-hard, so an efficient strategy to calculate the optimal moves would be a major breakthrough in computer science. Of course, there might be a greedy strategy, but not an efficient ...
dtldarek's user avatar
  • 1,065
39 votes
Accepted

lolcatz can haz ur infinit cheeseboard

Unless I'm mistaken, the result is Reading through the wall of text, the rules seemed a bit too complicated for it to be "just some random game", so figuring out the magic seemed ...
Bass's user avatar
  • 77.4k
35 votes
Accepted

12 Birds in the petshop

You need to ask
The Raven Queen's user avatar
35 votes

What is the minimum number of helpers that an explorer need to cross the desert?

The answer should be Here is how you do it.
APrough's user avatar
  • 7,679
32 votes
Accepted

16 pawns on a chess board with no three collinear: how do I go about solving this?

The Algoritm is : Then Here is the complete solution from Achim Flammenkamp Ph.D. There are totally 57 solutions
Jamal Senjaya's user avatar
31 votes
Accepted

Titanic Tic-Tac-Toe

The first player can always force a win. I wrote this Python script to analyze the tree of possible game states reachable from an empty starting board. No matter what the second player does, the ...
Kevin's user avatar
  • 6,449
31 votes
Accepted

Strategy for solving Flow Free puzzles

It's quite funny actually. I was terrible at these puzzles until I started writing this answer. To demonstrate the strategies that I completely and suddenly winged out of nowhere, I will solve the ...
greenturtle3141's user avatar
30 votes
Accepted

You trolls, get out of my party!

Solution: This was about the same thing I said before. But now... See Trenin's answer for a different formulation of the same approach, in case that one is easier to understand. Previous attempt at ...
Marius's user avatar
  • 18.1k
30 votes
Accepted

Find the heaviest and the second heaviest coins

fljx's user avatar
  • 16.2k
29 votes

Finding digits that sum to 15

The solution: The reason:
Deusovi's user avatar
  • 146k
29 votes
Accepted

Can you beat random?

Here's how you win in the long run Expected number of losses Thanks to Evargalo for fixing the last calculation.
hexomino's user avatar
  • 136k
28 votes
Accepted

How could Larry get his friends on a plane without knowing their weights?

Ben Barden's user avatar
  • 2,081
27 votes
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Playing with one Queen on a chessboard

We can work backwards to figure this out: Conclusion:
Deusovi's user avatar
  • 146k
27 votes
Accepted

1000 gold coins to share with the king

It might be possible to do a little better, but I think I can get Explanation:
tehtmi's user avatar
  • 3,241
27 votes

retsubkcolB Spelled Backwards

This is hugely inspired by @rhavelka's answer, so make sure to upvote him/her as well! Just found an alternative of where the phrases can come from:
Kevin Cruijssen's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible