Boat

Persons A, B, C, D and E would pass across a river using a boat.

• The boat can carry at most two people.
• When using the boat alone, the time required to pass across is 11 minutes for A, 7 minutes for B, 4 minutes for C, 2 minutes for D and 1 minute for E.
• When two people are on board, the time required to pass across is the difference between the times required for each of them to pass across alone.

In how many minutes in minimum can all pass across the river?

Example: If they use the boat as AB,A,AC,B,BD,C,CE they can pass across in 41 minutes (4+11+7+7+5+4+3=41).

answers: # 319     popularity: 69.4 %     difficulty: 33.3 %