Wednesday, July 1, 2009

Bridge Crossing

Remember the puzzle of a farmer crossing a river with a wolf, a goat and a cabbage? It is really a question of how the farmer ferries the wolf, goat and cabbage one at a time to the other side of the river without leaving the wolf and goat or the goat and the cabbage alone during the process.

Here is a puzzle of bridge crossing with some time constraints:

Four people A, B, C and D have to cross a bridge at night. The bridge is narrow so it can only allow two persons at a time. Since it is dark they have to use a flashlight when crossing the bridge. The speed of crossing the bridge for A, B, C and D are 1, 2, 5 and 10 minutes respectively. Their flash light can last only 17 minutes.
How do they cross the bridge?

No comments: