In an effort to encourage reader participation, I bring to you my first ever blog riddle. This riddle was told to me by Mike Metcalfe over dinner during the March meeting.
There was an evil king that wanted to kill 4 of his subjects, but worried that there would be an uprising if he simply had them executed, he decided to provide them with a way to escape their fate. What he did was to bury each of them in the ground up to their neck and he put a white or black hat on each of them. One of the subjects was placed behind a wall, so that he was not visible to the others. Example configuration:
Each prisoner could now only see what was in front of him. The king told the subjects that two of them were wearing white hats and two were wearing black hats, and if one of them could shout out the color of his own hat, all four of them would be set free. If any of them said something other than the color of his own hat, they would all be killed.
How do the prisoners escape?
The solution will be posted in the comments about a week from now, if someone out there doesn't post it first. UPDATE: Solution now available in the comments.