An adventurer found a locked treasure chest in a dungeon. He tracked down three brothers (each either a Liar or a Knight) one of whom has the key to open the chest.

Each made a statement:

A: I have the key to the chest.

B: I don't have the key to the chest.

C: B Doesn't have the key.

The adventurer knows that at least one of the three is a Liar, and at least one - a Knight. Who has the key?

B and C agree, so they are both Knights, or both liars. If A is a Knight, then he has the key, so all three must be knights, which violates the initial conditions (There is at least one liar).

So A is a liar, and B and C are knights. A does not have the key, B does not have the key, so C must have the key.

Posted by TomM on 2002-05-17 07:12:48