Engineering Interview Questions in Raleigh-Durham, NC | Glassdoor

# Engineering Interview Questions in Raleigh-Durham, NC

1,297

Engineering interview questions shared by candidates

## Top Interview Questions

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### Software Engineer at Cisco Systems was asked...

Oct 26, 2010
 Write C code to check if an integer is a power of 2 or not in a single line?5 Answersif( x & (x-1) == 0) { printf("Power of 2); }int isPowerOf2 = (i & 0x1) ? 0 : 1;Answer of Nov 9, 2010 is inappropriate. i=6 fails this code.Show More Responsesreturn !(x&(x-1)); returns "1" if x is power 2, returns "0" if x is not power of 2@SomeElse His code just checks if the number is even or odd.

### Software Engineer at Cisco Systems was asked...

Apr 3, 2010
 find number of 1's in a number4 Answersuse bitwise operator.while(number) { if(number & 0x01) count++; number=number >> 1; }int count1(int n) { int result=0; while(n&=(n-1)) result++; return ++result; } Complexity is O(m) where m is number of ones (NOT number of bits).Show More ResponsesFirst check if number is 0, if so return 0, else do the above function

### Software Engineer at NetApp was asked...

Dec 13, 2012
 Two trains, each moving at 20 miles per hour towards each other, are initially 60 miles apart. A bee starts at the front of one train, flies to the other train, then back to the first train, and so on. If the bee always flies at 30 miles per hour, how far does the bee fly before the trains collide?6 Answers45 miles. He was laid back about this question and wanted to see me thinking about it more than getting it right.time of collision=30/20=1.5hr distance fly by the bee= 30X1.5= 45miles45 miles is the wrong answer. The end points for the bee are constantly changing, so you can't just say 30X1.5Show More Responses@72min ..the bee collides with first train and starts traveling back @30miles/hour...when trains are 6 miles apart from collision point.. @90 min the collision occurs...so bee has 18min to travel from its collision in opposite direction...so 30mph * 18/60 = 9 miles towards collsion point(which is 6 miles apart). So it will be far by 3 miles.Other possibly correct answers: - The bee would die from the sudden impact with train 2 in 72 minutes after flying a total of 36 miles. - Oh you mean these bees have mastered inertialess flight - forget about the job and give me one of those to study! That aside... The one thing everyone left out of the answer was that enough information wasn't actually supplied to answer it 100% accurately and it has nothing to do with the fact that the two endpoints are moving. The issue is that while the 45 miles number may be "close enough" - to be 100% accurate you have to calculate the total number of traversals the bee can make in the time allotted and subtract it's body length 1 time for each of those traversals from the total.So the distance covered by both train in an hour is 40miles, to complete whole distance 1.5 hr required. and bee flies 45 miles in 1.5 hr. Ans: 45 miles

### Software Engineering Manager at NetApp was asked...

Mar 19, 2009
 A IQ question: I have 9 coins and 8 have the same weight and the last one is heavier. I also have a balance beam to weigh the coins with. I can only use the balance beam 2 times to find the heavier coin. How do you find the heavier coin?4 AnswersDivide the coins into 3 piles of 3. Weigh the first 2 piles. If they balance then the heavier coin is in the 3rd pile otherwise its on the balance beam. Take the heavier pile and place 1 coin on each end of the beam. If they are equal then the heavier coin is the 3rd coin else it is on the beam.OMG... It says the last coin was heavier! FIND THE LAST COIN...duh!@ranee : The answer given is correct. If the heavier coin is in the 3rd pile , then take any two from them and weigh them . If they are equal , you can easily say the last coin is the heaviest , otherwise the heaviest coin is one of the two being weighed. If in the first go , you can get hold of the heavier pile , do the same procedure as above. You can easily find it by using the balance twice.Show More ResponsesThis is a very famous question asked by both google and facebook in their interviews.

### Process Development Engineer at Cree was asked...

Oct 30, 2011
 Can Si be used to make LEDs ?3 AnswersSi can be used as a substrate in LEDs, but it cannot be used in the p-n junction because the bandgap energy is too small to produce visible light.Technically: Yes. But it has an indirect bandgap, so you really wouldn't want to.The energy bandgap of Si at room temperature is 1.12eV. Since the relationship between photon energy and wavelength is E(eV)=1.24/wavelength(micrometers), one can calculate that Si could emit a ligth in infrared optical spectrum: wavelength=1.24/1.12eV=1.11 micrometers. BUT, Si is indirect semiconductor! And therefore does not emit significant amounts of light due to the requirement of momentum conservation in optical transitions.

### Senior Software Engineer at Ericsson-Worldwide was asked...

Mar 24, 2009
 I had not expected to be asked logic questions, which made me nervous. The first one was a weigh nine items on a balancing scale to find the odd one out in the fewest scale uses3 AnswersSplit them into three groups of three, weigh two to determine the odd set out, then split that stack of three into three sets of one, and weigh two to find the single one out, requiring only two scale uses.The above strategy works only if you know whether the odd item is lighter or heavier. If you do not know how it differs, you will need more scale uses.111-111-114 <--- By weighing any of two sets, you get 114. 1-1-4 <----- By weighing any of two, you can find out 4.

### Process Engineer at Cree was asked...

Dec 4, 2013
 If an ice cube melts in water, does the water level rise or fall? Explain with details.3 AnswersNo, the water neither rises nor falls. The buoyancy of the ice does not affect the water level, it will raise the water level if you add ice to an already full glass of water, however because ice is lighter than the water (which is the oddity of water as an element versus other elements on the periodic table), the level stays the same.no, although the ice melts in a certain container if it is floating on a water the volume of ice is already condense on the water itself so water level will never changeno, the water level will remain the same because the displacement of the ice cube is what determines water level,not the volume of the portion of the ice cube that is submerged.

### Process Engineer at Cree was asked...

Dec 4, 2013
 If you're stuck in the middle of nowhere with a broken down car, how can you determine what the problem is?3 AnswersIt seems you have no gas.but when you encountered an engine trouble you cannot easily determine the problem without knowledge of it.objective: For example: diagnose & fix the car; or get out of nowhere; be at peace with being nowhere.Hmmmm, "If you're stuck in the middle of nowhere with a broken down car, how can you determine what the problem is?" A. The problem is obvious :0 You're stuck in the middle of nowhere and your car is broken down! Hopefully you have a cell phone with a cell tower nearby.

### Process Engineer at Cree was asked...

May 16, 2011
 Difference between turbo and cryo vacuum pump?2 AnswersA cryo pump uses a cryogenic fluid that entraps the gas molecules inside the chamber and freezes them below their freezing point. A cryo pump doesn't work very well with gases like He or H2. A turbo pump has a mechanical blade that is rotating at a very high speed and pulls the gases out of the system, imagine a jet engine on an airplane. The cryo pump is efficient if for ultra high vacuum ranges >10^-8 Torr compared to turbo. Both pumps require a small mechanical pump attached to the chamber to provide the lower level vacuum in the 10^-3 Torr range before they take over.A cryo pump uses a cryogenic fluid that entraps the gas molecules inside the chamber and freezes them below their freezing point. A cryo pump doesn't work very well with gases like He or H2. A turbo pump has a mechanical blade that is rotating at a very high speed and pulls the gases out of the system, imagine a jet engine on an airplane. The cryo pump is efficient if for ultra high vacuum ranges >10^-8 Torr compared to turbo. Both pumps require a small mechanical pump attached to the chamber to provide the lower level vacuum in the 10^-3 Torr range before they take over.

### Process Development Engineer at Cree was asked...

Mar 18, 2011
 How many barbers to cut men's hair in a city of 2 million people?2 Answers~3000 barbers. Work your way to the answer.I got the same answer, based on eight hour work days with 2 weeks of vacation each year. Based on the interviews I have read, if CREE hired the barbers, they would only need 1500, since they would be working 80-hour weeks.
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