100 prisoners are cryogenically frozen in solitary cells in a prison. Each day, one prisoner is randomly selected to be woken up, and taken to a room with a light bulb, and a switch. The prisoner can turn the light bulb on or off with the switch, or do nothing. Also, if the prisoner thinks that all other prisoners have been in the room before him, he can say so, and all the prisoners will be freed. However, if he's wrong, everyone is killed. So he can't guess. Before the prisoners are put in the cells they devise a system to know when everyone has gone. What is it? They can't write on the walls, and remember, they're cryogenically frozen so they don't know how many days have past. Also, the choosing of prisoners is completely random so one prisoner could theoretically go into the room 20 times in a row. This logic, and thaboss will give hints because it's very hard.

can't wait for another one

This riddle originally used bicycles and was called "53 Bicycles." I found it far too obvious, since "bicycle" is a more popular brand of cards and find 53 bicycles would be too rediculous to start with. I have an Eagle deck, so I changed it to eagles to make it a little harder to figure out. Looks like it worked.

"HE WORKS AT A BICYCLE SHOP! No... HE GOT RAN OVER BY A BICYCLE!"

Well that's me anyway.

100 prisoners are cryogenically frozen in solitary cells in a prison. Each day, one prisoner is randomly selected to be woken up, and taken to a room with a light bulb, and a switch. The prisoner can turn the light bulb on or off with the switch, or do nothing. Also, if the prisoner thinks that all other prisoners have been in the room before him, he can say so, and all the prisoners will be freed. However, if he's wrong, everyone is killed. So he can't guess. Before the prisoners are put in the cells they devise a system to know when everyone has gone. What is it? They can't write on the walls, and remember, they're cryogenically frozen so they don't know how many days have past. Also, the choosing of prisoners is completely random so one prisoner could theoretically go into the room 20 times in a row. This logic, and thaboss will give hints because it's very hard.

He feels the light bulb. If it is warm then he'll know another person has turned on the light.

but how he know that all prisoners have been in taht room?

I almost have it already. Check my logic.

The prisoners cannot communicate verbally, nor can they leave written messages. The messages must therefore be visible. The only way they can leave a visible message is with the lightbulb.

They can't choose to do nothing, because they would never know who had gone and when. They can't leave the lightbulb on permanently because the same would apply. If they alternate (one turns it on, one turns it off), they will lose the pattern the instant someone is used twice.

They must find a way to each leave an individual mark/clue, so that twenty marks will show that they have gone twenty times. If a prisoner is selected twice, he would do nothing because he has seen his mark.

He feels the light bulb. If it is warm then he'll know another person has turned on the light.

The prisoner needs to know that all the other prisoners have been in the room. And he could come in to the room and see the light bulb on. Perhaps thaboss explained it wrong. When a prisoner goes into the room he can turn the light bulb on, or leave it off. If the light bulb is already on (if another prisoner has been in the room and decided to turn it on), then he can turn it off, or do nothing. And the light bulb starts in the beginning as off.

He feels the light bulb. If it is warm then he'll know another person has turned on the light.

That would only work the first time. After that, the lightbulb would always be warm and they could never know when all twenty had gone.

MattEmAngel's logic is near perfect.

Something HAS to change every time. There would be no way to establish a pattern when you could only leave three clues: on, off, of warm. A person would have no way to know they had gone more than once, and the next person would have no way to know how many had gone before him unless there was a way to leave twenty different marks. No pattern could compensate with so many random variables.

well here is mine kinda like Matt ones

One prisoner goes in room and trun light on then ohter one come and trun it off
but if same prisoner goes into room again and he sees the light is on/off like he left it.

well if it's not right then i gonna wait for some clues