49 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.
  • 33.3k
46 votes
Accepted

Five loaves and the extra traveller

Such an old chestnut! Each of them eats 5/3 loaves. The first traveler contributes 3 loaves, eats 5/3 himself, and gives 4/3 to the extra traveler. The second traveler contributes 2 loaves, eats 5/3 ...
  • 44.8k
39 votes

Too Many Damn Buffalos

Wikipedia has a nice article on this. Buffalo buffalo (buffalo from Buffalo NY) [that] Buffalo buffalo buffalo (that the buffalo from Buffalo NY bully) buffalo Buffalo buffalo (are bullying ...
37 votes
Accepted

The Comforting Death Message

I've seen a variation of this before:
  • 1,174
37 votes

Two Clever and Thirsty Soda Packaging Workers

You and Roger are out of luck. Let the side length of the cube be $s$, so there are $s^3$ sodas. If $s$ is odd, then there will be an odd number of sodas left over, since $s^3$ is odd, and removing 4 ...
  • 31.5k
35 votes
Accepted

Which data file is genuine?

The real data set is: First clue: Second clue:
  • 16.9k
32 votes

Five loaves and the extra traveller

Another way of getting the same answer as Gamow is to have each traveller notionally pay \$5. That gives them a pot of \$15, from which they distribute the money to those who provided the bread. They ...
  • 3,004
31 votes
Accepted

Ernie and the Pirates of the Caribbean

In order to solve this problem, I used a combination of a flood-fill algorithm and Dijkstra's algorithm. I set up a large grid of cells over the map. Each cell remembers its current distance and its ...
  • 15.9k
28 votes
Accepted

The telltale code

I don't have time to flesh out every detail right now, but the story is clearly Some of the clues that give it away: Some more: In the back-story:
  • 1,620
26 votes
Accepted

What's the password?

The kingdom is guarded from foreigners, therefore the password is based on native language (which is of course English:):) ).
  • 15.9k
22 votes
Accepted

Uncle Mort's Idiots

I would suggest the combination Firstly, the "asking" code combined with the row of numbers suggests that they spelled out a word in ASCII code. The numbers on the front of the safe only go to 100, ...
  • 3,572
20 votes
Accepted

Given these numbers, find the secret word

Assuming a mistake in the problem layout, we could get something with some significance: The error would be And with this
  • 12.6k
18 votes

Too Many Damn Buffalos

Let's replace the place with New York Let's replace the verb with bully Let's keep the animal as buffalo Original: ...
  • 1,201
18 votes

I'm stumped on a simple roman numeral puzzle

Given that there's little context, it's hard to give a definitive answer, but I'd have to guess that the answer you are looking for is: This can be found by:
  • 13.7k
17 votes
Accepted

The Laziest Surveyor

He calculated the area using Pick's Theorem. Area = (number of internal grid points) + (half the number of boundary points) - 1 The area is $149 + \frac{21}{2} ...
  • 13k
17 votes
Accepted

The Secret Agent Who Got Shot

This one is very literal. Also,
  • 3,040
17 votes
Accepted

Reverse hangman #12

I think the answer is: H C P L
  • 6,047
16 votes
Accepted

A grammatically valid sentence in English containing seven "that"'s in a row?

Found it: "It is true for all that that that that that that that refers to is not the same that that that that refers to." Meaning: It is true for all that, that that "that" ...
  • 12.7k
16 votes
Accepted

Guess the object - What Am I Riddle (Part 3)

Answer: Explanation:
  • 503
16 votes
Accepted

Find the composite poison in the wine bottles

On the first day Use 10 groups of 2 prisoner and number them 0.0, 0.1, 1.0, 1.1, 2.0, ..., 8.1, 9.0, 9.1. Prisoner a.b drinks from bottles with $\left\lfloor\frac{index}{2^a}\right\rfloor\%2=b$. ...
  • 849
16 votes
Accepted

Two lists of favorite words

Your likes the word "Listen". Here's why:
  • 51.2k
15 votes
Accepted

Too Many Damn Buffalos

Basically, it's "buffalo who reside in Buffalo, NY that bully other buffalo that also live there, also bully themselves."
15 votes
Accepted

First day of school

He saw a male student walk out of the door marked "Boys" - in this case, he either walked out of the Cafeteria or the Girls' bathroom. He must've exited the Cafeteria (because he cannot use the Girls' ...
  • 12.7k
15 votes
Accepted

Two Clever and Thirsty Soda Packaging Workers

Let's say $N$ is the length of the side of the cube. After their operation, you and Roger drink 2 sodas, but you still need a number of bottles which is multiple of 4, otherwise it wouldn't fit the 4-...
  • 12.5k
15 votes

Find the composite poison in the wine bottles

A simple solution for 1000 prisoners 998 dead Number all prisoners and bottles 1-1000, and have each prisoner drink from ALL bottles except their matching number. The 2 surviving prisoners have ...
  • 341
15 votes
Accepted

5 Letter Word, Removing letters

This is an old one. The answer is: Because: And, of course, you can
  • 13.7k
15 votes
Accepted

Ernie and the Superconducting Boxes

First, we need to figure what is the minimum amount of superconductor that we'll lose when making the cut. Optimally, we can cut the large cube net into two smaller cube nets without any waste at all. ...
  • 69.5k
14 votes
Accepted

The box with the curious inscriptions

Them's five volumes and three sections alright. Blurb for the Volumes and Sections: Colophon. This puzzle's apparent construction. Missed clues:   (Would the hints have been necessary in the ...
  • 21.5k
14 votes
Accepted

Grandma's Simple Puzzle Box

Few easy steps to solve it:
  • 5,146

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