Brainteaser

[stan394]

There is an on/off switch inside a room, controlling a light bulb. The warden will randomly pick one out of 30 prisoners to go inside the room. The prisoner can turn on or off the light bulb, or leave it as is. However, among the 30 prisoners, they don't know who went in and who didn't. The warden will keep randomly picking a prisoner to go inside the room. The goal of the group of 30 prisoners is to find someone to go up to the warden and say for sure all 30 of them have already gone inside the room at least once.

How can they do that?

- The initial state of the light bulb is not known
- The 30 prisoners can discuss a strategy before the game begins
- The temperature of the light bulb cannot be used as information
- Any prisoner will know how many times he himself has gone into the room.
- Prisoners cannot talk among themselves once the game begins

EDIT:
- Prisoners cannot leave anything inside the room, because the warden doesn't allow them to
- The warden did keep track of who went in or not
- The 30 prisoners were separated in 30 different cells. The warden took a random prisoner to the room and accompanied him back to his own cell. The prisoners NEVER see each other.

 

[stan394]

nobody wants to take a stab at this? 😛

 

[kyzen]

leave a left shoe in the room every time they go in, till there are 30 left shoes in there?

 

[stan394]

Originally posted by: kyzen
leave a left shoe in the room every time they go in, till there are 30 left shoes in there?

haha, good one, but no 😛

 

[crystal]

If they can't talk, how can they, "find someone to go up to the warden and say for sure all 30 of them have already gone inside the room at least once."

If they can, then they already know who already went in or not. duh!!!

 

[stan394]

Originally posted by: crystal
If they can't talk, how can they, "find someone to go up to the warden and say for sure all 30 of them have already gone inside the room at least once."

If they can, then they already know who already went in or not. duh!!!

Let's phrase it as "at a certain point, one prisoner will go up to the warden and say "all 30 of us have been to the room", without consulting each other"

 

[NikPreviousAcct]

After coming out of the room, they stand on the opposite side of the warden from the original group. When everybody goes from one side to the other, there ya go.

 

[imported_Cameron]

The prisoner just tells the warden at a random time because the warden has not been counting either.

 

[kyzen]

i don't see what's wrong with the shoes... 😛

 

[NikPreviousAcct]

Maybe there's a door on the other side of the room. Warden is on one side and the prisoners are on the other. They walk in through one door, then exit through the other. When all have passed through, there ya go.

 

[RaynorWolfcastle]

it all relies on creating a code with the light switch, while everyone counts the number of people that have gone in to decode it. I hate perfectly logical being puzzles.

 

[YOyoYOhowsDAjello]

First guy turns the light off, then the rest of the prisoners attack the warden and then they all escape.

 

[NikPreviousAcct]

:laugh:

 

[stan394]

I love ATOT 😀

 

[Zoblefu]

Will the first person know he is the first person in the room?

 

[stan394]

Originally posted by: Zoblefu
Will the first person know he is the first person in the room?

nope. the only information he got is whether the light bulb is on or off, as for any other prisoners.

 

[imported_Cameron]

Ok put some more thought into it...

Eveyone initially turns the light on and one guy keeps turning it off.
Once he reaches 30 everyone has been there.

 

[YOyoYOhowsDAjello]

Originally posted by: Cameron
Ok put some more thought into it...

Eveyone initially turns the light on and one guy keeps turning it off.
Once he reaches 30 everyone has been there.

Once he reaches 30 what?

EDIT: oh, I think I get what you're saying

 

[stan394]

Originally posted by: Cameron
Ok put some more thought into it...

Eveyone initially turns the light on and one guy keeps turning it off.
Once he reaches 30 everyone has been there.

what if the same guy keeps being picked to the room?

 

[imported_Cameron]

the 30th time that he turns it off

 

[imported_Cameron]

Originally posted by: stan394

Originally posted by: Cameron
Ok put some more thought into it...

Eveyone initially turns the light on and one guy keeps turning it off.
Once he reaches 30 everyone has been there.

what if the same guy keeps being picked to the room?

he leaves it on and waits for the one person that only turns the light off to be picked.

 

[stan394]

Originally posted by: Cameron

Originally posted by: stan394

Originally posted by: Cameron
Ok put some more thought into it...

Eveyone initially turns the light on and one guy keeps turning it off.
Once he reaches 30 everyone has been there.

what if the same guy keeps being picked to the room?

he leaves it on and waits for the one person that only turns the light off to be picked.

Cameron is the winner!!! 🙂

 

[YOyoYOhowsDAjello]

Wait, no, I don't get it.

 

[Zoblefu]

That was exactly what I was thinking, but this doesn't work if you don't know the initial state of the light....

If the light starts on, and the guy that can turn it off goes in there first, he would have to count it as a person going in there and he would be off by one.

 

[YOyoYOhowsDAjello]

Can you explain this more, I'm not getting it 🙁