The Grey Labyrinth is a collection of puzzles, riddles, mind games, paradoxes and other intellectually challenging diversions. Related topics: puzzle games, logic puzzles, lateral thinking puzzles, philosophy, mind benders, brain teasers, word problems, conundrums, 3d puzzles, spatial reasoning, intelligence tests, mathematical diversions, paradoxes, physics problems, reasoning, math, science.

milkshake · Daedalian Member

One hundred geniuses have been imprisoned for life. Now, their evil, insane prison gaurd is allowing them a chance to escape.

He will line the prisoners up single file with each prisoner only being able to see the prisoners in front of them. If any prisoner attempts to break the line, everyone will be shot. (This prison gaurd is very evil.) On each of the prisoner's head, the gaurd will place one hat. It will be, at complete random, either a white hat or a black hat. The number of white hats and black hats does not have to be at all equal.

Starting with the prisoner in back, each prisoner will be allowed to say either "white" or "black." If they say their hat color, they are set free. If they do not, they die. At threat of death, the prisoners cannot convey any information to eachother besides what they guess- white or black- and, of course, whether they were correct or not (based on whether they are set free.)

The evil prison gaurd explains the game to the prisoners. He is allowing the genius prisoners ten minutes to agree upon their strategy. But the evil prison gaurd won't let the prisoners "cheat" in any way with any external items or any external way of conveying information, or he will kill them all. And he will most certainly find out about any "cheating." The only thing the prisoners are able to do is agree upon a plan for getting the most of them out alive.

How can the prisoners save the maximum amount of people?

JDTAY · obseletes now

Complain to the Federal Bureau of Prisons.

Zag · Tired of his old title

They are all saved, by, of course, pelting the guards with chestnuts.

Here it is in the "Chestnuts" thread.

milkshake · Daedalian Member

Oh, this was already posted/is well known, sorry! And here I really thought I was posting a cool puzzle which people might not have heard of. Cannibal

(It's a good puzzle, though. People who haven't heard it before are usually pretty stumped by it. I wonder how many of these "chestnuts" we puzzle-minded folk were able to figure out on our first go?).

You guys sure know alot of puzzles here. Revenge most foul!

Zag · Tired of his old title

Generally, VSP is intended for original puzzles. You are welcome to post ones that you read or heard somewhere, but you should give credit if you know the original author, or at least say that you read it elsewhere, but really liked it so you wanted to share. (It's ok that you didn't, this one time. We realize you didn't know. It's the firing squad in the future, however. Enthusiastic Grin

) Collectively, we've heard probably any which you are not getting from an original source, though.

A few years back there was a new member who jumped in and posted a bunch of "original" puzzles that were really good, quite clever, and none of us had seen before. It wasn't a failure-to-disclose, he clearly claimed that he had written them himself, and several of us were quite impressed. Of course, the brilliant minds here were able to solve them, after some work, but we all liked them and looked forward to his new installments.

It turned out that he was getting them from another site which was in another language, and he was just translating them. This other site was running a competition with actual cash prizes for the person solving the most, and you'll never guess who was in the lead so far! (He wasn't even clever enough to use a different username.)

Amb · Amb the Hitched.

I would like to buy that man a drink. Thats flipping clever, and he could easily appear on the Apprentice under Donald Trump.

ralphmerridew · Daedalian Member

When did all that happen?

milkshake · Daedalian Member

Wow that's pretty darn sneaky.

I'm afraid I wouldn't even know where to start if looking for the original mind behind this puzzle but thanks for filling me in, Zag!

milkshake · Daedalian Member

Has anyone heard this one before? More of a simple math experiment than a puzzle, perse:

Say there are 100 light bulbs labeled 1-100, all off, and 100 people.

The 1st person goes through and flips the switch on every single light bulb, turning them all on.
The 2nd person flips all the switches that are a multiple of two, turning off every other light bulb, starting with the second.
The 3rd person flips every third switch (all the multiples of three).
And so on up to the 100th person who flips the last lightbulb on/off.

After everyone has had there turn, which light bulbs will be on (and which will be off)?

JDTAY · obseletes now

Damnit, milkshake, that stuff is going to cause global warming.

milkshake · Daedalian Member

Great that's another "chestnut" too isn't it. (Or just too easy.)

Oh well. Razz

Zag · Tired of his old title

You're forgiven for not finding it in the Chestnuts thread, because it is worded quite differently -- rather than switches controlling lights, they are lockers left open or closed. I only know it because I just went through the last half of the thread, making links in the first note to each puzzle.