Originally posted by XanthosNZ
There are 100 prisoners. In one hour the warden will pick one of them at random and kill that person (I'm assuming no other prisoner knows which prisoner was killed). They also know that tomorrow (and every day from here on) one prisoner will be selected at random and led into a room where they have the option of toggling a light switch. If while in this r ...[text shortened]... t isolated so they must plan a strategy in the next hour.
What strategy should they employ?
This is not the problem first stated. However, I think this might work;
Two prisoners are labelled A and B. All prisoners need to remember who A and B are. All prisoners need to keep track of the days, more precisely if the number of days passed since this day is odd or even. I assume the light is off at the start.
Prisoner A turns the light on on an even day, prisoner B does so on an odd day. Otherwise none of them do anything.
The light remains off until either prisoner A or B has been in the room. If on a day a prisoner finds the light on, he only needs to know if the previous day number was even or odd.
If is was even, prisoner A was there the day before. If it was odd, prisoner B was there.
Only one of the two can be shot in the beginning, leaving the other alive to continue as planned.
If the light was on at the start, the prisoners will have to turn the light off, instead of on.