Find minimum time to cross bridge with flashlight

A group of people must cross a bridge at night with one flashlight. The bridge can hold at most two people at a time.

• If two people cross together, they move at the speed of the slower person.
• The flashlight must always be carried when crossing.
• Everyone starts on the same side and all must end on the other side.

Given an array t[] of crossing times (positive integers) for each person, compute the minimum total time needed for everyone to cross.

Clarify assumptions you will use (e.g., can people return, constraints on n, etc.) and describe an efficient algorithm.