IrishEyes

This puzzle is not as tough as it sounds, but the setup will make you feel like a rocket scientist when you get it. Allegedly, this is one of the questions for potential Microsoft employees. I must warn you, you can really get caught up trying to solve this problem.

Reportedly, one guy solved it by writing a program, although that took him 37 minutes to develop (compiled and ran on the 1st try though). Another guy solved it in three minutes. A group of 50, at Motorola, couldn't figure it out at all. See how long it takes you.

Here we go... "U2" has a concert that starts in 17 minutes and they must all cross a bridge to get there. All four men begin on the same side of the bridge. You must help them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them. The flashlight must be walked back and forth, it cannot be thrown, etc. Each band member walks at a different speed. A pair must walk together at the rate of the slower man's pace:


*Bono: - 1 minute to cross
*Edge: - 2 minutes to cross
*Adam:- 5 minutes to cross
*Larry: - 10 minutes to cross


For example: if Bono and Larry walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Larry then returns with the flashlight, a total of 20 minutes have passed and you havefailed the mission.

Notes: There is no trick behind this. It is the simple movement of resources in the appropriate order. There are two known answers to this problem. This is based on a question Microsoft gives to all prospective employees.

Note: Microsoft expect you to answer this question in under 5 minutes!

BTW - I haven't tried it yet for fear of failing and I don't have the answer.
Unless I solve it myself that is.


Good Luck!

pbsaj

Bono & Edge cross = 2 mins (total = 2)
Bono goes back = 1 mins (total = 3)
Larry & Adam cross = 10 mins (total = 13)
Edge goes back = 2 mins (total = 15)
Bono & Edge cross = 2 mins (total = 17)

Rudy

You can choose to take the easy way out and write the solution that way or you can really challenge your brain and write it this way:

u2.pdf

IrishEyes

Ye b'stard. This was supposed to go on for weeks. The usual - if a train leaves blahblah at 09:10 and travels at mach 4 for .324 light years, how long will it take a sperm whale to digest a cargo ship of molasses at 34 degrees latitude 15 degrees longitude..

I had Edge going back with the torch first.

Nice one.

PS - Did u get the job with M$ or had u seen this before. We'll see how many blondes are out there if they continue to try and answer the puzzle.

Rudy

Irish, you forgot that anyone here can easily find the answer on the net. Did you really think it would go on for weeks?

Hatchd

Reading comprehension apparently isnt my best subject. I tried it for 10 minutes and couldnt get it. Then I read the answer and felt like an idiot. I thought when two people crosses that the slowest one always had to go back and get the other guy. Example, Edge and Bono cross in 2 minutes, that it would also take 2 minutes to get back. Oh well, im stupid. lol

Iceman

That was easy.
Have found that on the net a couple years earlier...

Rudy

And, of course, you can solve it one other way by switching the order of who goes back. In other words:

Bono & Edge cross = 2 mins (total = 2)
Edge goes back = 2 mins (total = 4)
Larry & Adam cross = 10 mins (total = 14)
Bono goes back = 1 mins (total = 15)
Bono & Edge cross = 2 mins (total = 17)

IrishEyes

Well if someone had a slow internet access, YES.
The internet IS a wonderful thing.

PS - Y'all are a bunch of Internet cheats.

pbsaj

Ah - but where did you find the puzzle in the first place!