NVIDIA Interview Question: Four people, (A, B, C, and D)... | Glassdoor

Interview Question

Architect Interview Hillsboro, OR

Four people, (A, B, C, and D) need to get across a river

 , and there is only one boat. The boat can only hold two people at a time and will only go as fast as the slowest person in the boat. If it takes A one minute to cross, B two minutes, C five minutes, and D seven minutes, what is the shortest time for all 4 people to cross the river?
logic, analytical reasoning

Interview Answer

3 Answers


14 minutes is the fastest time. A and B go first (2 min), then A comes back (3 min), next C and D goes (10 min), then B comes back (12 min), finally A and B go across again (14 min). The trick is hiding C's time within D.

Interview Candidate on Sep 22, 2009

The other guy has got it wrong . When C and D go how come B comes back ?
1. D and A go . A comes back - = 7+1 = = 8 min
2. A and C go . A comes back = 5+1 = 6 min
3 A and B go . = 2 min

Total time 16 min

alok on Oct 17, 2012

Well, Whar the above person means is,

A+B go ---> 2 mins
A comes back --> 1 min
C+D go --> 7 mins
B comes back --> 2 mins
A+B go --> 2 mins.
Total --> 14 mins

B comes back because he has crossed the river and is on the other side and can come back.

Anonymous on Sep 26, 2014

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