Crossing Bridge Interview Puzzle

By | April 27, 2014

This is again a classic interview puzzle .Asked by many tech giants. Probably you have heard this puzzle earlier ,but the reason we wrote a post on this puzzle is because many candidates even who have heard this puzzle fail to answer this puzzle in the interview. Here’s the Puzzle :

Problem: Four people are on this side of the bridge. the bridge will be destroyed by a bomb in 17 minutes. everyone has to get across before that. Problem is that it’s dark and so you can’t cross the bridge without a flashlight, and they only have one flashlight. Plus the bridge is only big enough for two people to cross at once. The four people walk at different speeds: A fella is so fast it only takes him 1 minute to cross the bridge, B takes 2 minutes, C 5 minutes, the D it takes 10 minutes to cross the bridge. when two people cross the bridge together (sharing the flashlight),
they both walk at the slower person’s pace. can they all get across before the bridge blows up? Mentioning the speeds once again :
Person A: 1 minute
Person B: 2 minutes
Person C: 5 minutes
Person D:10 minutes

Hint : try different combinations and see in which kind of solutions your total time is reducing and try to improve on that.

for more interesting puzzles see our puzzles page

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