All but the last person could get free.
The last person tells the parity of number of RED(or BLACK) hat before
him.(and pray God's forgiveness :<)
Then the rest can tell the color of his own hat using what he sees
before him and what he/she hears from behind.
On 2011-3-3 16:18, freecoder wrote:
You are one of 20 prisoners on death row with the execution date set
for tomorrow.
Your king is a ruthless man who likes to toy with his people's
miseries. He comes to your cell today and tells you:
“I’m gonna give you prisoners a chance to go free tomorrow. You will
all stand in a row (queue) before the executioner and we will put a
hat on your head, either a red or a black one. Of course you will not
be able to see the color of your own hat; you will only be able to see
the prisoners in front of you with their hats on; you will not be
allowed to look back or communicate together in any way (talking,
touching.....)
(The prisoner in the back will be able to see the 19 prisoners in
front of him
The one in front of him will be able to see 18…)
Starting with the last person in the row, the one who can see
everybody in front of him, he will be asked a simple question: WHAT IS
THE COLOR OF YOUR HAT?
He will be only allowed to answer “BLACK” or “RED”. If he says
anything else you will ALL be executed immediately.
If he guesses the right color of the hat on his head he is set free,
otherwise he is put to death. And we move on to the one in front of
him and ask him the same question and so on…
Well, good luck tomorrow, HA HA HA HA HA HA!”
Now since you all can communicate freely during the night, can you
find a way to guarantee the freedom of some prisoners tomorrow? How
many?
--
You received this message because you are subscribed to the Google Groups "Algorithm
Geeks" group.
To post to this group, send email to algogeeks@googlegroups.com.
To unsubscribe from this group, send email to
algogeeks+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/algogeeks?hl=en.
