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Troll Problem


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3 replies to this topic

#1 nam517

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Posted 11 September 2007 - 06:40 AM

Can anyone help me solve this puzzle?
If you can that would be great.
Thank You

You are walking in a forest and come to a fork in the road. There is a troll standing there. You can either go right or left. One way leads you out of the forest safely and the other way leads you to a very painful death by wild animals. You can ask the troll one question only. Now, here's the tricky part.... The troll tells the truth every other day. For example, if the troll tells the truth today, he will lie tomorrow. If he lies today, he will tell the trut tomorrow. You don't know which day he's on (i.e. truth day or lie day). You have one and only question to save your life. What will ask the troll?
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#2 bonanova

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Posted 11 September 2007 - 07:02 AM

We assume the troll knows which road is safe.

Ask: "Which road would you have told me yesterday was safe?"

He'll either lie about telling you the truth or tell the truth about lying to you.
Either way, he'll point to the dangerous road.

Then take the other road.
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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

#3 rookie1ja

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Posted 11 September 2007 - 01:18 PM

I have one puzzle with the same principle ... check Honestants and Swindlecants III.
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#4 unreality

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Posted 11 September 2007 - 08:18 PM

Most Liar/Truthteller riddles with two (or three) directions/doors/paths/etc to go are based on this princriple, ie, asking one man what the other would say (in this case, the "other" man is the liar or truthteller of yesterday because he was different yesterday)
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