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Topic: 3 spiders and a psychic fly and five prisoners (Read 937 times) |
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chetangarg
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3 spiders and a psychic fly and five prisoners
« on: Jun 21st, 2007, 6:31am » |
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Plz help me....
1. 5 prisoners are going to take green beans from a bag with 100 green beans. They will do it one by one. No communication is allowed between them. but they can count the green beans left in the bag. They must take out at least one bean each time. Those who take the largest and the smallest number of beans will die.
Question: who is most possible to survive.
hints: 1. they are all smart people.
2. they will try to survive first and then try to kill more people.
3. they donot need to take out all 100 beans
4. all prisoners who have the same largest or smallest number will die.
The riddle doesnot mention the condition when there is no bean left in the bag. I assume the prisoner get 0 beans in that case.
2. Three spiders and a fly are moving along the edges of a regular tetrahedron. The spiders are trying to catch the fly. Unfortunately the fly is invisible, hyperintelligent and psychic. Fortunately, the fly is also very slightly slower than the spiders (say epsilon slower). The spiders know they have caught the fly only when one of them runs over it.
So, the rules:
First the spiders decide on starting positions and the paths they will take on the edges (and corners) of the tetrahedron. Deterministic paths only please (the fly is intelligent and psychic enough to know the results of any coin tosses the spiders may make).
The fly, being psychic, knows ahead of time what the starting position and path of the spiders will be, and so chooses its starting position and path accordingly.
Can the spiders catch the fly?
I am sorry if the thread to these puzzles already exists.
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towr
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Re: 3 spiders and a psychic fly and five prisoners
« Reply #1 on: Jun 21st, 2007, 7:17am » |
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on Jun 21st, 2007, 6:31am, chetangarg wrote:| I am sorry if the thread to these puzzles already exists. |
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I'm pretty sure btoh are on the site, and the last certainly is: http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_med ium;action=display;num=1149638217
Quote:1. 5 prisoners are going to take green beans from a bag with 100 green beans. They will do it one by one. No communication is allowed between them. but they can count the green beans left in the bag. They must take out at least one bean each time. Those who take the largest and the smallest number of beans will die.
Question: who is most possible to survive.
hints: 1. they are all smart people.
2. they will try to survive first and then try to kill more people.
3. they do not need to take out all 100 beans
4. all prisoners who have the same largest or smallest number will die. |
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Does 2 mean that if multiple people have the same maximum or minimum value they all die?
And if someone is going to die anyway, will he aim to take as many as possible with him?
In any case, it seems you could let a computer run this easily enough.
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