The Eccentric Warden

Here's a puzzle I discovered recently, it was presented to me as a "Google Challenge", supposedly a question Google recruiters use to test the problem solving abilities of candidates.

Twenty prisoners are serving time in a backwater jail led by an eccentric warden. The warden has decided to play a game with the prisoners. He will lead the prisoners one at a time into a room with two switches. Each switch (the left and right one) may be in one of two states (ON or OFF). The prisoner must flip one and only one of the switches and then he is led back to his cell.

The warden decides in advance the methodology he is using to select which prisoner visits the room next. This methodology is kept a secret by the warden and the only guarantee is that if the game goes on forever, each prisoner will visit the room an infinite number of times.

The warden tells the prisoners these rules before the game begins, and says that any prisoner can stop the game before flipping a switch by declaring that all twenty prisoners have visited the room. If he is right, all the prisoners are set free, otherwise they are all executed!

All the prisoners are kept in isolation for the duration of the game and cannot communicate other than through using and observing the switches. However, before the game begins, the prisoners can meet to discuss their strategy. What should their strategy be?

Keep in mind that the warden may choose a methodology such as: "19 of the prisoners visit the room randomly until 10 years has elapsed. Afterwards, all 20 prisoners visit the room regularly." So it wouldn't be wise to use probability in your strategy, such as: "Well after 8 years, chances are we've all been to the room."

Green Mushroom Award: Professor Fizzwizzle

You may be wondering why I haven't been posting recently. Well, let's just say that I've been very busy.



On an unrelated topic, I want to tell you about a new game I've dicovered. Professor Fizzwizzle is a strange name for one of the best puzzle games I've ever played. The object of the game is to move the professor from the entrance of each level to the exit all the while avoiding Rage-bots (the professor's mechanical creations gone bad) who begin chasing the professor if they see him.

The professor can move left and right and climb ladders, but he can't jump. He can also push crates, but only one at a time. Barrels are like crates except they keep rolling once they are pushed. Magnets are also like crates except the positive ends stick to metal objects, and can repel other magnets.



Crates can be pushed over grass, but can't be pushed over sand. Barrels stop rolling on sand but can still be pushed. Also, on ice all objects continue to slide. Trampolines repel objects that slide/roll into them.

Platforms attatched to pulleys complicate things greatly, as do the colored switches that open correspondingly colored doors when objects move over them. To make things even more puzzling, there are inflatable objects you can get that allow you to place at a later time crates, barrels and magnets wherever you're currently standing.



There are also powerups such as the EMP which can be used once to disable Rage-bots that are chasing you, and temporarily cause magnets to loose their normal EM behavior. The Whistle can be used once to attract the attention of distant Rage-bots, and the Frost-Gun can be used to freeze crates, barrels and magnets to make them more mobile.

The game comes with great graphics, smooth gameplay, decent music and best of all, a fully featured level editor. You can get a demo at http://www.grubbygames.com which actually has many levels.