eBay Interview Question: Given 4 people who each take ... | Glassdoor

Interview Question

Associate Manager Buyer Analytics Group Interview San Jose, CA

Given 4 people who each take different times to cross a

  bridge (10 mins, 5mins, 2mins and 1 min), what's the least amount of time taken to cross the bridge if only 2 can cross at a time and a flashlight is needed for each trip across.
brain teaser, analytical

Interview Answer

1 Answer


Kinda tricky. It's 17 minutes.
First 1,2 cross, 1 takes the flashlight back. (=3 mins)
Then 10,5 cross. 2 (who is still on the other side) takes the flashlight back. (=another 12 mins)
Then 1,2 cross again. (=another 2 mins)
So it's 3+12+2=17 minutes in total.

Vanessa on Jan 15, 2013

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