Monthly Archives: August 2016


Crossing bridge with torch

Four people need to cross an old bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without torch.

  • The bridge is only strong enough to support two people at a time.
  • Not all people take the same time to cross the bridge.
  • Times for each person: 1 min, 2 mins, 7 mins and 10 mins respectively.

What is the shortest time needed for all four of them to cross the bridge?