Interview questions gone wrong...
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If that is of some comfort to you: I screwed up a simple binary search in an interview once.
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it. -Brian Kernighan
Most people do. I saw something recently about how most binary search implementations don't work if the start and end pointers are above 2GB in memory. Normally the algorithm finds the mid-point by adding start and end together, then dividing by 2 - if the start and end pointers are above 2GB, you get an integer overflow and the 'mid point' ends up right down near address 0. This doesn't work very well. Most of us will still be fine on Win32 because it's hard to get a user-mode pointer above 2GB. You can only do it by booting with the /3GB switch (on OSs which support it) and linking the executable with /LARGEADDRESSAWARE.
Stability. What an interesting concept. -- Chris Maunder
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Marc Clifton wrote:
My answer would have been, why are you testing to see if a number is a power of 2?
Easy, for mathematical factorization like Mersenne primes. You change your algorithm if it is a power of two +/-1.
"I know which side I want to win regardless of how many wrongs they have to commit to achieve it." - Stan Shannon
Strangely, I'm not in the habit of doing that every day as a programmer. (If you happen to be programming strong cryptographic key generation and wish to check that the key you generated is strong enough to withstand easy factorization, then go ahead. I'll use CryptoAPI where someone else has already written it.)
Stability. What an interesting concept. -- Chris Maunder
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Strangely, I'm not in the habit of doing that every day as a programmer. (If you happen to be programming strong cryptographic key generation and wish to check that the key you generated is strong enough to withstand easy factorization, then go ahead. I'll use CryptoAPI where someone else has already written it.)
Stability. What an interesting concept. -- Chris Maunder
I agree... Ive been writing both production and shrink wrap code for over 11 years and I have always looked up anything that I didnt know. Why memorize something that you may never use? I'd rather have a developer on my team that has a good attitude, understands the business problems that they are trying to solve and knows where to look when they dont know the answer to a quetsion...
Jake-
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Strangely, I'm not in the habit of doing that every day as a programmer. (If you happen to be programming strong cryptographic key generation and wish to check that the key you generated is strong enough to withstand easy factorization, then go ahead. I'll use CryptoAPI where someone else has already written it.)
Stability. What an interesting concept. -- Chris Maunder
I agree that those types of questions are probably more about the interviewer's ego than finding the skill level of the applicant. But, that question made me think, a little.:doh: Consider this. All powers of 2, in binary are in the following form: 01, 10, 100, 1000, 10000 etc... which of course is 1, 2, 4, 8, 16, etc... So the easy way to tell is just any number that in binary is a single 1 followed by all zeros.
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Nishant Sivakumar wrote:
How will that help determine if a number is a power of 2? Powers of 2 are 1,2,4,8,16,32...
Oops, perhaps he meant multiple of 2. :-O At least, that's what I understood. :~ Alvaro
If [God] knows what we are going to do then we have no free will and are just characters in a play written by him. Without free will, morality for humans makes no sense. Without free will and morality, any sort of punishment or reward system loses any justification. Heaven and hell would be places where [God] could watch the souls he created, predestined just for eternal happiness or agony. - Mark Thomas
The interviewer meant POWER of 2 ie..1,2,4,8,16,32 and i believe, (((x&(x-1))+1)==2*x) is the right answer.... coz any power of 2 will be of the form 00001000.... and x-1 will of form 00000111.... Now when we do x&(x-1)...ie. bitwise and we get 00001000... 00000111... ------------ 00001111... whichh is 1 less than 0001000 ...(x*2)
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Fuzzychaos wrote:
Anyone have other mixed up interview questions?
"Have you ever had problems with a co-worker?" Yeah, just don't answer that one. Definitely don't launch into long stories. :-o
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Yeah, that's like "do I look fat in these pants?" or "do you like that girl?" There are around 14,000 answers to those questions, all of which are incorrect.
Try code model generation tools at BoneSoft.com.
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Had an interview over the phone today. Totally bunged the question. They asked for a test to check if a number is a power of 2 and I answered it as a test to see if it was divisible by 2! Should have been (x && !(x & (x - 1))). What a dolt I be! I was so nervous I messed up other simple ones too. Needless to say I didn't get the job failing the technical questions. Anyone have other mixed up interview questions?
Jeremy Pemberton-Pigott
A programmer with a dream can accomplish anything. So, start by implementing your castle in the clouds and then working on its interface to a foundation :-D Quote by: Jeremy Pemberton-Pigott
New Dawn EngineeringHad a phone interview once where on question 3 they said, "Can you tell me in code how to determine if any given number is a prime number in the most optimized algorythm? Go ahead, we'll wait..." Phukers! My reply started with something like "Um uhhh durhh..." Didn't get that job, perhaps a blessing. Then recently, had a phone interview where they gave me several language questions, then asked "If you needed a windows app to listen on another thread for a web service response, how would you implement that design-wise?" My response started off just about the same. I drew blank. My brain was screaming "NOT ENOUGH INFORMATION!" After the call, I thought of a couple good answers, but it sucks when that happens in an interview because then you're thinking about solutions for that stupid scenario for DAYS. Jury's still out on that position...
Try code model generation tools at BoneSoft.com.
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The interviewer meant POWER of 2 ie..1,2,4,8,16,32 and i believe, (((x&(x-1))+1)==2*x) is the right answer.... coz any power of 2 will be of the form 00001000.... and x-1 will of form 00000111.... Now when we do x&(x-1)...ie. bitwise and we get 00001000... 00000111... ------------ 00001111... whichh is 1 less than 0001000 ...(x*2)
AmitDey wrote:
Now when we do x&(x-1)...ie. bitwise and we get 00001000... 00000111... ------------ 00001111...
:confused: This "&" is the bitwise operator for the logical function AND, so, with it you would get 00001000... 00000111... ----------- with operator & 00000000... What you need is the bitwise operator for the logical function OR. The operator is "|" so this operator would be the correct one, hence the expression is "x|(x-1)" 00001000... 00000111... ----------- with operator | 00001111...
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The interviewer meant POWER of 2 ie..1,2,4,8,16,32 and i believe, (((x&(x-1))+1)==2*x) is the right answer.... coz any power of 2 will be of the form 00001000.... and x-1 will of form 00000111.... Now when we do x&(x-1)...ie. bitwise and we get 00001000... 00000111... ------------ 00001111... whichh is 1 less than 0001000 ...(x*2)
I think you meant x|(x-1)... But there is another way: x&(~(x-1))==x 00001000... = x 00000111... = x-1 11111000... = ~(x-1) 00001000... = x&(~(x-1)) This should work even if x = 2 (...0000001) or x = (1000000...) Mikon Dosogne
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I think you meant x|(x-1)... But there is another way: x&(~(x-1))==x 00001000... = x 00000111... = x-1 11111000... = ~(x-1) 00001000... = x&(~(x-1)) This should work even if x = 2 (...0000001) or x = (1000000...) Mikon Dosogne
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Even better! But did you google the answer? ;)
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I agree that those types of questions are probably more about the interviewer's ego than finding the skill level of the applicant. But, that question made me think, a little.:doh: Consider this. All powers of 2, in binary are in the following form: 01, 10, 100, 1000, 10000 etc... which of course is 1, 2, 4, 8, 16, etc... So the easy way to tell is just any number that in binary is a single 1 followed by all zeros.
sum all binary and result should be 1 eg : 8= 1000 (bin) 1+0+0+0 =1 // convert binary to string replace '0' with '' check if string length is 1 // ;) and you can explain them this is the most optimesed way it can be cause all the interviwer are not techies they are mostly from hr dept with some questoins (limited) and even if they belong programming they dont prove you wrong so you are right ;) -- modified at 13:24 Tuesday 19th September, 2006
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Even better! But did you google the answer? ;)
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Had an interview over the phone today. Totally bunged the question. They asked for a test to check if a number is a power of 2 and I answered it as a test to see if it was divisible by 2! Should have been (x && !(x & (x - 1))). What a dolt I be! I was so nervous I messed up other simple ones too. Needless to say I didn't get the job failing the technical questions. Anyone have other mixed up interview questions?
Jeremy Pemberton-Pigott
A programmer with a dream can accomplish anything. So, start by implementing your castle in the clouds and then working on its interface to a foundation :-D Quote by: Jeremy Pemberton-Pigott
New Dawn EngineeringI was asked in an interview to write the algorithm to find n numbers in the Fibonacci series, or whatever. I misunderstood them so I accidentally wrote a program that printed on the screen a large phallic figure, and to decode the words corresponding to the acronym "YUCK FOU", and quickly left.
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Right bracket, x, logical and, not, right bracket, x, binary and, right bracet, x - 1, left bracket, left bracket, left bracket ;)
Pablo Sometimes I think there's no reason to get out of bed . . . then I feel wet, and I realize there is.
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Polymorpher wrote:
Pablo Sometimes I think there's no reason to get out of bed . . . then I feel wet, and I realize there is.
:laugh::omg::wtf:
We made the buttons on the screen look so good you'll want to lick them. Steve Jobs
LOL, I found that on a homer simpson sight.;P
Pablo Sometimes I think there's no reason to get out of bed . . . then I feel wet, and I realize there is.
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sum all binary and result should be 1 eg : 8= 1000 (bin) 1+0+0+0 =1 // convert binary to string replace '0' with '' check if string length is 1 // ;) and you can explain them this is the most optimesed way it can be cause all the interviwer are not techies they are mostly from hr dept with some questoins (limited) and even if they belong programming they dont prove you wrong so you are right ;) -- modified at 13:24 Tuesday 19th September, 2006
Dim Number As Integer = ??? Dim Temp As Integer = 1 Do Until Temp > Number Temp <<= 1 Loop While Temp > 0 If Number < Temp Then Return False Else Number -= Temp End If Temp >>= 1 End While Return True ...Unless there is a simpler way to convert an integer to binary I think the original way was faster
Pablo Sometimes I think there's no reason to get out of bed . . . then I feel wet, and I realize there is.