The weekly Puzzler from Click and Clack, the Car Talk guys, was so hard that they extended it a week and gave some hints. I woke up this morning at 5:30 and knew the answer without having thought about it consciously. Next on my dream agenda: Re-discover benzine's structure!
Unfortunately, when I re-checked the puzzle this morning, I found I'd significantly altered its terms, a case of having the right answer to the wrong question.
Anyway, here's the puzzle:
The warden meets with 23 new prisoners when they arrive. He tells them, "You may meet today and plan a strategy. But after today, you will be in isolated cells and will have no communication with one another.
"In the prison is a switch room, which contains two light switches labeled A and B, each of which can be in either the 'on' or the 'off' position. I am not telling you their present positions. The switches are not connected to anything.
"After today, from time to time whenever I feel so inclined, I will select one prisoner at random and escort him to the switch room. This prisoner will select one of the two switches and reverse its position. He must move one, but only one of the switches. He can't move both but he can't move none either. Then he'll be led back to his cell.
"No one else will enter the switch room until I lead the next prisoner there, and he'll be instructed to do the same thing. I'm going to choose prisoners at random. I may choose the same guy three times in a row, or I may jump around and come back.
"But, given enough time, everyone will eventually visit the switch room as many times as everyone else. At any time anyone of you may declare to me, 'We have all visited the switch room.'
"If it is true, then you will all be set free. If it is false, and somebody has not yet visited the switch room, you will be fed to the alligators."
And then we get three hints:
Hint number 1: A sixth grader could figure this puzzler out.
Hint B: Take a long-term perspective.
And Hint III: Solve the puzzler for three prisoners.
You can submit your answer to Car Talk...but you gotta tell me first.
Comments
Great. Thanks Dave. I thought I was going to get a good night sleep. But not with that Puzzler racing around my head.
Posted by: Richard Giles | February 11, 2003 09:22 AM
Now I too am racking my brain. Hope this doesn't cause me to forget Dave Winer's blog thing this evening!
Posted by: Betsy Devine | February 11, 2003 04:37 PM
44
Posted by: Michael O'Connor Clarke | February 12, 2003 10:49 AM
I posted what I think the anser is. Comments are welcome.
Posted by: Wayne | February 12, 2003 01:28 PM
Wayne, where di you post it?
Posted by: Anonymous | February 12, 2003 03:53 PM
Here you go...
http://makeashorterlink.com/?S18D21673
Posted by: John | February 13, 2003 09:56 PM
I really have a problem with the answer that was posted today. Nowhere in the problem as stated does it say that the strategy session COULD NOT be held IN the switch room! Therefore, if the prisoners hold it IN the switch room, they will be out of there in no time!
Posted by: Jeannie | February 17, 2003 10:15 AM
I really have a problem with the answer that was posted today. Nowhere in the problem as stated does it say that the strategy session COULD NOT be held IN the switch room! Therefore, if the prisoners hold it IN the switch room, they will be out of there in no time!
Posted by: Jeannie | February 17, 2003 10:15 AM
I really have a problem with the answer that was posted today. Nowhere in the problem as stated does it say that the strategy session COULD NOT be held IN the switch room! Therefore, if the prisoners hold it IN the switch room, they will be out of there in no time!
Posted by: Jeannie | February 17, 2003 10:16 AM
I really have a problem with the answer that was posted today. Nowhere in the problem as stated does it say that the strategy session COULD NOT be held IN the switch room! Therefore, if the prisoners hold it IN the switch room, they will be out of there in no time!
Posted by: Jeannie | February 17, 2003 10:16 AM
That gives us a pretty good starting point to understand a lot more about variables, and that's what we'll be examining next lesson. Those new variable types I promised last lesson will finally make an appearance, and we'll examine a few concepts that we'll use to organize our data into more meaningful structures, a sort of precursor to the objects that Cocoa works with. And we'll delve a little bit more into the fun things we can do by looking at those ever-present bits in a few new ways.
Posted by: Lucy | January 13, 2004 09:53 AM
what is this
28= D in a S
Posted by: Cash | May 9, 2006 08:07 AM
We may use 1 switch for a tag and the other just for changing state as it is given the prisoner have to change the state of 1 switch.
Chose a leader who will count (count what?? is explained below).
So lets say we chose switch A in the on conditions as a tag that a new prisoner has visited the room.
Only the leader can turn off the switch A and adds 1 to his count every time he turns it off. But he himslef doesnot turns it on (so as not to confuse himself with the count). If leader finds it in the off state(he visited consecutively) already he should change the state of switch B
Everytime a new prisoner comes if he finds the switch A in off condition(that means the count has been taken in account) he can switch it on. If he finds it in on condition then change the state of B.
This way the leader will count the number of on states of switch A and then change it to off state. Taking in account ,if the starting state of switch A is on. He may count it as a visited prisoner. So counting this case and 22 changed on states(he himself is the 23rd person) = 23 is the count which the leader got to reach to ensure that all of them has visited.
Posted by: Sunil Kumar | April 18, 2007 01:53 PM