194 votes
Accepted

Lock your computer when you walk away!

I guess this is Because
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  • 1,526
111 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 ...
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  • 1,428
89 votes

Game of Life: Kill the Sun

I found a sun destroyer with just 10 cells filled! It takes 39 generations. As animation:
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  • 871
81 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 :).
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  • 6,216
79 votes
Accepted

What famous line does this Linux command line represent?

The answer is echo -e 'AAAAHHH!!!\a' > /dev/null # #
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77 votes
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James Bond : No Access

Well perhaps
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  • 9,461
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, $(...
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  • 13.3k
65 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 ...
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  • 15.6k
58 votes
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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 ...
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57 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 ...
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  • 571
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 ...
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52 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 ...
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51 votes
Accepted

What famous dialogue does this Java code represent?

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48 votes
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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
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47 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 ...
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47 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 ...
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46 votes
Accepted

Chuck Norris vs. This Question

This looks like because also, X should be ...
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  • 10.8k
42 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 ...
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  • 36.1k
41 votes
Accepted

What comes next in the sequence?

The next number in the sequence is: The sequence he is following is:
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  • 711
40 votes

Game of Life: Kill the Sun

I made another one, with a mere 8 cells. It takes 44 generations. As animation:
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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:
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36 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:
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  • 6,216
35 votes
Accepted

Wife can't figure out husband's secret account password

John's new password is: The word keeps in the "money" theme. It is for a bank account (money-themed) and his previous password was BROKE (money-themed). John's ...
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34 votes
Accepted

A Robot's Last Words

Answer: Explanation: Here are the functions for the output (in Java). Output 1 = !((!C)|C) Output 2 = (!C)|C Output 3 = !((!C)|C) Output 4 = (A|B)&C Output 5 = (!(A^B))&(!(B^C)) Output 6 = ((!A)&(B^...
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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:
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  • 13k
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 ...
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  • 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 ...
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  • 9,542
30 votes
Accepted

The Legend of Sally the Cow

The ending is
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29 votes
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The great puzzle

I think it was and the quote is Explanation for those not familiar with SSH: Explanation for the year:
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  • 5,531

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