> > There are no tricks  this is a straightforward problem. > > U2 have a concert that starts soon 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 > that crosses the bridge, either 1 or 2 people, must have > the flashlight with them. The flashlight must be carried > 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 by the time they get to the other side > of the bridge. If Larry then returns with the flashlight, a > total of 20 minutes have passed. What is the shortest > amount of time to get all four men across the bridge? > > There is no trick to this. It is a simple movement of > resources in the appropriate order. > > > > > >
