U2 Puzzle:

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 C 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 ot takes you.

Here we go...


"U2" has a consert 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 flashligt must be walked back and forth, it cannot be thrown etc.
Each member walks at a different speed. A pair must walk together at
the rate of the slowest 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 have failed 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 expects you to answer this question in under 5
minutes!
Good Luck!