The bridge and torch problem (also known as The Midnight Train and Dangerous crossing) is a logic puzzle that deals with four people, a bridge, and a torch. It is one of the categories of river crossing puzzles, where a number of objects must move across a river, with some constraints.
Four people come to a river in the night. There is a narrow bridge, but it can only hold two people at a time. They have one torch and, because it's night, the torch has to be used when crossing the bridge. Person A can cross the bridge in 1 minute, B in 2 minutes, C in 5 minutes, and D in 10 minutes. When two people cross the bridge together, they must move at the slower person's pace. The question is, what is the minimum time taken by them to cross the bridge?
