Note: 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. They expect you to answer this question in under 5 minutes.
"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 have failed the mission.
I have yet to figure this out. The only way I think I'm going to do this is to make a chart of all possible combinations.
Bono, flashlight + Larry, Bono goes back before Larry has crossed so 10 mins have pass, bono takes adam past and goes back before adam gets there 5 mins have passed, and finally he can take edge across = 17 mins.
No, you must have two people go together, and it's not impossible. It says CLEARLY the flashlight must be walked back and forth, and it does not shine all the way across the bridge. There is no tricks, just simple and correct movements.