Truthtellers and Liars

[Banfa]

I'm sure you've all heard this one

You come to a T junction, 1 road leads to certain doom in the pit of invalid memory accesses while the other leads to a chocolate mountain (or in mmccarthy's case a Whiskey Lake). There are no sign posts but there are 2 people at the cross roads, one is wearing a red T-shirt and the other is wearing a blue T-shirt.

There is a wooden sign saying, "1 person always tells the truth and the other always lies. But we are not telling you who is who. Meuuuuuuuuu Ha Ha Haaa".

You can not go back the way you came because you are being chased by a BOFH.

You may ask 1 question that can be answered yes or no (you don't know how you know this, the knowledge just appeared in your mind as you took in the scene. Almost as if it was POKEd there).

What question should you ask to find out which path to take?

Like a said well known, in fact it has even appeared in the odd film (Labyrinth), so if that was too easy for you try this one

You come to a another T junction, 1 road leads to even more certain doom in the dungeon of middle managers while the other leads to the oasis of coffee and forgetting about work. There are no sign posts but there are 3 people at the cross roads, one is wearing a red T-shirt, one is wearing a blue T-shirt, and the last one is wearing a Hawkwind T-shirt.

There is a wooden sign saying, "1 person always tells the truth, 1 person always lies and 1 person randomly answers yes or no. But we are not telling you who is who. MEEEEUuuuuuuuu Ha Ha Haaaaaaaaaaaaaa".

You can not go back the way you came because a particularly vicious virus is in the process of erasing that road.

You may ask 2 questions that can be answered yes or no (you know this because floating above the scene is a bright pink flashing neon sign saying so).

What questions should you ask of who to find out which path to take?

[subashini Thiyagarajan]

HI banfa,

I don't know whether my understanding is correct.

it is very easy

i ll ask truth teller


Is this(left) road leads to cholcolate mountain?


Truth teller answer me yes or no
so i ll go ahead

if two question allowed
i 'll ask lier the same question .if i get different answer with full confirmation i'll go ahead!!

any comments

[Banfa]

HI banfa,

I don't know whether my understanding is correct.

it is very easy

i ll ask truth teller


Is this(left) road leads to cholcolate mountain?


Truth teller answer me yes or no
so i ll go ahead

if two question allowed
i 'll ask lier the same question .if i get different answer with full confirmation i'll go ahead!!

any comments

Yes I have a comment, I have completely written the questions wrong. Your solution works the way I originally wrote the questions but I am about to re-write them to actually be what they should be, then please try again.

[AdrianH]

Yes I have a comment, I have completely written the questions wrong. Your solution works the way I originally wrote the questions but I am about to re-write them to actually be what they should be, then please try again.

I know the answer to your first question.

The answer to the second one is not as clear. If I were ask the one in the red "what would the one in the blue say if I asked the one in the Hawkwind, ``does the left path lead to certain doom?''" and that person is not the random one, how will that one react? Will it ask the one in blue to ask the one in Hawkwind? Or will it not answer because it cannot do so without violating it's yes/no ability?


Adrian

[Banfa]

The answer to the second one is not as clear. If I were ask the one in the red "what would the one in the blue say if I asked the one in the Hawkwind, ``does the left path lead to certain doom?''" and that person is not the random one, how will that one react? Will it ask the one in blue to ask the one in Hawkwind? Or will it not answer because it cannot do so without violating it's yes/no ability?

You will always get an answer, if any one of the people in the chain of people involved in your question is the random answerer than the answer you get will be random.

[subashini Thiyagarajan]

please repeat the correct question again

i feel this is not to think a lot to answer ........

[Banfa]

please repeat the correct question again

i feel this is not to think a lot to answer ........

I edited the original posts to contain the correct answers.

As a clue I will say that in both questions the people you meet at the T junction already know who each other are and how they will respond.

[Ganon11]

I have a creative answer to the first question;

First step: Randomly punch one of the people. If you have punched the Truthful one, he will inevitably start screaming in pain, saying, "Ow, it hurts!" etc. etc. If you have punched the liar, he will vehemently deny that you hurt him at all. Either way, you will know who the Truthful one is.

Second step: Ask the truthteller which way leads to certain doom, and take the other path.

I'm the winner!

[AdrianH]

I have a creative answer to the first question;

First step: Randomly punch one of the people. If you have punched the Truthful one, he will inevitably start screaming in pain, saying, "Ow, it hurts!" etc. etc. If you have punched the liar, he will vehemently deny that you hurt him at all. Either way, you will know who the Truthful one is.

Second step: Ask the truthteller which way leads to certain doom, and take the other path.

I'm the winner!

ROFLMAO. :D


Adrian

[Banfa]

I have a creative answer to the first question;

First step: Randomly punch one of the people. If you have punched the Truthful one, he will inevitably start screaming in pain, saying, "Ow, it hurts!" etc. etc. If you have punched the liar, he will vehemently deny that you hurt him at all. Either way, you will know who the Truthful one is.

Second step: Ask the truthteller which way leads to certain doom, and take the other path.

I'm the winner!

It is typical of a C++ programmer to approach a (fairly) elegant logic problem with brute force :p

[AdrianH]

I have a creative answer to the first question;

First step: Randomly punch one of the people. If you have punched the Truthful one, he will inevitably start screaming in pain, saying, "Ow, it hurts!" etc. etc. If you have punched the liar, he will vehemently deny that you hurt him at all. Either way, you will know who the Truthful one is.

Ahhh, but what happens if these are ninja-kung-fu people. Then they'd whip yer ass. :D


Adrian

[tolkienarda]

Answer to question one
Ask: "If i were to ask for the road to wisky lake what direction would the other person point right",
the liar will lie about the way the truth teller will point and then point to the bad place, and the truth teller will also point to the bad place. so of course go the oposite way they both point

eric