198
votes
Accepted
114
votes
XOR - Is it possible to get a, b, c from a⊕b, b⊕c, a⊕c?
If you're given just a⊕b and b⊕c, then you can calculate
...
- 1,468
93
votes
Game of Life: Kill the Sun
I found a sun destroyer with just 10 cells filled!
It takes 39 generations.
As animation:
- 911
83
votes
Accepted
Game of Life: Kill the Sun
The following is a solution with 34 generations:
And, yes, it was really fun to play with it :).
- 6,376
70
votes
XOR - Is it possible to get a, b, c from a⊕b, b⊕c, a⊕c?
This is not possible.
Consider the two cases where a, b and c are all true or all false. Now in both cases we have
a⊕b = b⊕c = a⊕c = false
And more generally, $(...
- 13.4k
68
votes
Game of Life: Kill the Sun
6 cells, 43 and 50 generations
I found 11 unique (up to reflection) 6-cell solutions:
By the first generation of evolution, they form two identical groups:
The first, fourth, and last two patterns ...
- 18.6k
60
votes
Game of Life: Kill the Sun
23 cells, 41 generations, humorous answer
Sorry, I couldn't resist it... The pulsar dies on "magical command" after 41 generations but it takes 23 initial cells.
I apologise for the ...
- 601
59
votes
Accepted
Game of Life: Move the Sun
6 cells, 111 generations
I found 12 unique (up to reflection) 6-cell solutions:
They all work by the same method as my previous 8-cell solution, forming a house one cell below the top of the base ...
- 18.6k
53
votes
Game of Life: Move the Sun
I have a solution:
I shamelessly stole the upper part from BaSzAt's 8-cell sun destroyer, and, by trial and error, found a 7-cell lower part that generates a new pulsar without interfering with the ...
- 3,189
53
votes
Debugging with printf()
Works in gcc, with 3 characters on the line above:
Side note:
To reactivate the printf() add a blank line above it.
Another side note:
As ...
- 21.8k
50
votes
Accepted
Debugging with printf()
Well, he can do it by adding
on the line before. So that's
Or, slightly better, exploit the fact that
and make that first line
for
- 116k
50
votes
Accepted
Selective attention: an unusual game
Brace yourself to realise that this puzzle is even cleverer than you first think... This is a special one...
The seven-letter answer is:
Why? Firstly:
Next, notice:
To replace the underscores with ...
- 128k
48
votes
Game of Life: Kill the Sun
In case anyone is wondering, here is my own solution, which takes 38 generations.
(NB: When I made this puzzle, I had no idea if it's even generally solvable. It took me 4 or 5 hours, while having ...
- 5,637
46
votes
Accepted
44
votes
Accepted
Fwd: Re: Karen is missing!
Ok, an excellent puzzle like this deserves a complete answer, so I'm going to bring everything together and fill in the missing blanks...
First, we have to determine if there's actually a reason to ...
- 37.1k
41
votes
Game of Life: Kill the Sun
I made another one, with a mere 8 cells. It takes 44 generations.
As animation:
- 5,637
39
votes
Accepted
Little bits of food
The answer is
Following Dan Russell's partial answer:
Thanks to @f'' in the comments, the interpretation of this is:
- 21.6k
37
votes
Game of Life: Kill the Sun
More humorous solutions (destroy methods)
Sorry, I couldn't resist too
Call 911 :) 20 cells, 38 generations:
Use AI (artificial intelligence), 62 generations:
- 6,376
33
votes
Who stole the bitcoins?
Partial - No time to finish it now
As was mentioned by Beastly Gerbil the QR-Code decodes to:
This points to a new image:
With this image:
Next Step:
- 13.2k
32
votes
Computer riddle: I treat vars like D
I like the other answers, but there's a clue that they really don't capture well. This answer is similar to the others, but I think hits some of the clues more accurately than the other answers.
You ...
- 1,571
32
votes
Accepted
Bar-coded Message (Reverse Engineering)
Here you can find the files found in the recovered compressed file.
The ogg file is distorted, maybe somebody with better audio editing skills can figure out something. The pictures and filenames ...
- 9,592
32
votes
Accepted
Regular Expressions
/straw$/; # (3,5,5)
/\d+safety\d+/; # (6,6,2,7)
/^\@[67]+$/; # (10,2,2,5,3,6)
/(my |the high)way/; # (2,3,2,3,7)
/(Thomas|Richard|Harold)...
- 15.3k
30
votes
Accepted
29
votes
Accepted
The great puzzle
I think it was
and the quote is
Explanation for those not familiar with SSH:
Explanation for the year:
- 5,637
29
votes
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:
- 1,630
28
votes
28
votes
decipher RGXWSTLSQLITL where (ABCDEF=QWERTY)
If ABCDEF = QWERTY, then:
1 Q W E R T Y U I O P = A B C D E F G H I J
...
- 116k
Only top scored, non community-wiki answers of a minimum length are eligible