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Topic: Black Box (Read 384 times) |
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Jeremiah Smith
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Beep!
Posts: 172
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I suppose a good portion of you are familiar with the pencil-and-paper game Black Box, where the object is find "atoms" that have been hidden in a grid by shooting "rays" into the grid. For those not familiar, there's a somewhat decent copy of the rules here: http://www.tough-puzzlers.com/Black%20Box.htm and a spiffy Java applet hither: http://www.supermaze.com/blackbox.html
Anyway, give yourself a moment or two to familiarize yourself with the rules...
*waits patiently*
Okay. Now for the puzzle. Given a 20x20 grid, what's the minimum amount of atoms required to ensure that any ray fired into the grid will be absorbed? Also, how should they be placed?
Hint 1. This can actually be generalized to any size grid very easily.
Hint 2. Note the behavior at the edges.
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| « Last Edit: May 30th, 2003, 7:37am by Jeremiah Smith » |
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Icarus
wu::riddles Moderator
Uberpuzzler
Boldly going where even angels fear to tread.
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Posts: 4863
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Re: Black Box
« Reply #1 on: May 31st, 2003, 8:39am » |
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I have a question concerning the rules. Suppose an atom is located in one of the perimeter cells. What happens to a ray that enters the box adjacent to the atom? The rules given don't cover this situation. To be consistent with the rules, the ray would be deflected before it even enters the box. Is this the case?
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"Pi goes on and on and on ...
And e is just as cursed.
I wonder: Which is larger
When their digits are reversed? " - Anonymous
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Leo Broukhis
Senior Riddler
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Posts: 459
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Re: Black Box
« Reply #2 on: May 31st, 2003, 8:55am » |
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Yes, a ray is considered deflected even if it goes parallel to the edge without entering the box. Given that, the answer is 76.
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