Sudoku

sudoku9

Puzzle

Crossing the Bridge ?

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. 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.What is the shortest time needed for all four of them to cross the bridge?

Answer :

Minimum 17 mins would need for all of them to cross the bridge.

Lets name them as 1_Min ,2_Min,7_Min and 10_Min respectively.

Step 1 : 1_min and 2_min crosses and 1_min returns with torch ;time needed 2+1 minutes

Step 2 : 7_min and 10_min crosses and 2_min returns with torch ; time needed 10+2 minutes

step 3 : 1_min and 2_min crosses and time needed 2 minutes

So total time needed 17 minutes