Four persons (A, B, C, D) have to cross a rope bridge in the middle of a darkest night. They have only one flashlight. The rope bridge is not strong enough to carry more than 2 people. All 4 of them take different times to cross the bridge. 'A' takes 1 minute to cross the bridge. 'B' takes 2 minutes to cross the bridge. 'C' takes 5 minutes to cross the bridge. 'D' takes 10 minutes to cross the bridge. The night is so dark, it is impossible to cross the bridge without the flashlight. And also 2 persons are crossing the bridge together, the faster person has to slow down to accompany the slower person.
For example, if first, 'A' (1 minute) and 'C' (5 minutes) decided to cross the bridge together then it will take 5 minutes to cross the bridge together as 'A' has to slow down to accompany 'C' with flashlight. Also as it is impossible to cross the bridge without the flashlight, After 'A' and 'C' crossed the bridge, either 'A' or 'C' has to come back to other side of the bridge with the flashlight.
Can you calculate the minimum time required in total to cross the bridge?

Indranil MaitiProfile