Four persons crossing a bridge

♠ Posted by GeekyFry in , at 9:42 AM

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?




Possible Solution:
1 and 2 cross
2 comes back
7 and 10 cross
1 comes back
1 and 2 cross  :)

Total time = 2 + 2 + 10 + 1 + 2 = 17 mins

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