A question to IT KBers, part III

[Street Gerbil]

Don't be silly; you and xerxesdaphat came up with the same correct solution.

I knew I started this thread for a reason. Admittedly it never occurred to me that at an interview I can just write a couple of lines of pseudocode instead of tediously chasing all the pointers and making sure that the counters are not off by one or that I haven't forgot to declare a loop counter (my favorite pen-and-paper based coding bug). Thanks for the tip!

Ever sat in front of a computer running bespoke software of some sort and watched a display inexplicably crawl across the screen for no obvious reason, instead of doing stuff quickly?

On the other hand I've seen programs crashing in the production environment after a programmer has decided that an infrastructure class is not fancy enough and implemented some kind of ultra-fast search algorithm without realizing that if a user hits cancel at exactly the right time, the algorithm will be asked to search for an empty string, something that UtString.search() was perfectly capable of doing in a correct way. I've seen how the program suddenly prints (or worse, emails) a contract requiring a customer to pay by February 30th, because the programmer thought he knows better (or just was not aware that he needs to call UtDate.addMonth()).

[jrandom]

On the other hand I've seen programs crashing in the production environment after a programmer has decided that an infrastructure class is not fancy enough...

Yeah, I hate that too. Can't stand cunts who think they know it all and try to make everything as complicated as possible.

(No, I'm not one of them. At least, I try not to be.)

[imdying]

Yes, in balance the force must be.

[Ixion]

Nah, that can cause an overflow.

This one should not:

a = a ^ b;
b = a ^ b;
a = a ^ b;

Ahh the beauty of XOR...

No-one said the variables were numeric. Or even convertable to numeric. Nor was the language specified. Nor the compiler. With modern multithreading OSs and optimising compilers you cannot be sure that those three statements will be executed sequentially.

I wouldn't want to work for a company that placed such stock on conjuring tricks. Once upon a time memory and storage cost enormous sums.I worked with a system that had only 128 bytes of memory (yes, bytes) Minimising variables and such was important. 4 bytes saved was dollars save. Now, that's not true .Hardware is cheap. If an extra variable is needed declare it. The cost of the extra RAM will be saved 100 times over in the time saving the first time someone has to maintain the program.

What the expiring gentleman said. The purpose of any software development is to add to the profitability of the business (or equivalent for government departments etc). Reinventing wheels is not profit enhancing. And the most beautiful tightly coded application is useless if it doesn't arrive until three months after it was needed.

[enigma51]

Yeah, I hate that too. Can't stand cunts who think they know it all and try to make everything as complicated as possible.

(No, I'm not one of them. At least, I try not to be.)

Yet your interview question says otherwise

[Street Gerbil]

Yet your interview question says otherwise

Well, I think that is a bit unfair. Even if you haven't touched algorithms for 10 years, you can sketch the nodes and the pointers and figure out how it should work. The program printing permutations of a string is less obvious because there are many ways of doing it and you need to figure out the one easiest to implement.

[jrandom]

Yet your interview question says otherwise

It's a simple question designed to figure out whether someone wanting to work for a company has a minimal level of brainpower and is familiar with certain basic computer programming concepts.

Don't read too much into it.

Fact is, all other arguments about how one should use libraries aside, if an applicant can't solve the problem as stated, they're a dumbfuck who needs to be in a different line of work.

The point is not that one shouldn't ever reinvent the wheel - the point is that one should be capable of reinventing the wheel, and then choose not to do so when it's not necessary.

No matter how fast the processor or how enormous the memory or comprehensive the class library of basic data-manipulation functions, a dumbfuck programmer can still quite happily implement, f'rinstance, a data-processing routine which uses up all that memory when it should use a tenth of it, and takes days to run when it should take minutes.

It happens all the time out there, and I've always tried to do my employers a favour by weeding those people out in interviews.

Would you mind letting your hackles back down now?

[jrandom]

4 bytes saved was dollars save. Now, that's not true .Hardware is cheap. If an extra variable is needed declare it. The cost of the extra RAM will be saved 100 times over in the time saving the first time someone has to maintain the program.

I believe I made an identical comment earlier in this discussion.

What I like to point out to people is the difference between optimising linearly (saving a byte here or there, or taking a chunk out of the execution time of a loop) which is generally not worth bothering with, and optimising by reducing the computational complexity of your algorithm (looking at a problem in a whole new way which means you can finish processing in ten minutes instead of a week).

It's the latter that always has been and always will be important.

And that's why I like to see job applicants solving the list-reversal problem with a single pass through the list, instead of looping across it once for every node, etc. It's the latter type of thinking that leaves computers churning for weeks when they could be finished on a lunchbreak.

Fred Brooks, the author of The Mythical Man-Month (which is a great read) wrote an excellent essay a while back called 'No Silver Bullet - Essence and Accidents of Software Engineering' about these concepts and how they apply in the efficiency of the industry.

It's out there on the innuhneh, go read it y'all.

[scracha]

Reminds me of an interview I had in Edinburgh once.

Interviewer: "you have to write a program to read data from a tape drive. How would you verify the data has been written correctly?"
Moi: "I'd use a 32 bit CRC to validate the data"
Interviewer: "but what if the CRC was wrong"
Moi: "eh?"
Interviewer: "but what if the CRC doesn't detect the error"
Moi: "but the odds of that are less than 1 in 4 billion"
Interviewer: "ok but what if this happened"
Moi: "umm....I'd use a 64 bit CRC"
Interviewer: "can you think of another way"
Moi: "Oh for fucks sake"

Tosser started waffling about linked lists and reading in the data backwards or some $hite like that.

I didn't get that job.

[lager zombie]

10 Fuck Off
20 Goto 10

[avgas]

"Show me in 30 seconds how you would write a program to maintain the temperature in a room"

- heres a tip, its not a technical question, all he wants is a structure diagram showing that you consider when fans/heaters should be changed while watch a dynamic element (temperture).
- He doesn't care what variables you use, only what the structure of the code should looks like.
- He doesn't care if you f-up a loop, use a while instead of the logic....etc he just wants to see if you can consider what is involved and plan before you leap.

FYI recruitment agents are assholes, i specifically said that i was after an electronics/software job - and ended up getting into the power industry.
They get paid commission by jamming the circle into a square.

[lager zombie]

Most recruitment agencies scan CV's for keywords.

Get the tech / business / logic balance wrong and they'll wipe their arse on the cv before giving it to the hedonistic receptionist to lick off then throw in the bin.

[jrandom]

Interviewer: "can you think of another way"

"Reed-Solomon codes, motherfucker, but who could be arsed. And I'm outta here, cos you're a twat."

Edit: Agreed re. 99% of recruitment agents being scum-sucking oxygen thieves.

[enigma51]

It's a simple question designed to figure out whether someone wanting to work for a company has a minimal level of brainpower and is familiar with certain basic computer programming concepts.

Don't read too much into it.

Fact is, all other arguments about how one should use libraries aside, if an applicant can't solve the problem as stated, they're a dumbfuck who needs to be in a different line of work.

The point is not that one shouldn't ever reinvent the wheel - the point is that one should be capable of reinventing the wheel, and then choose not to do so when it's not necessary.

No matter how fast the processor or how enormous the memory or comprehensive the class library of basic data-manipulation functions, a dumbfuck programmer can still quite happily implement, f'rinstance, a data-processing routine which uses up all that memory when it should use a tenth of it, and takes days to run when it should take minutes.

It happens all the time out there, and I've always tried to do my employers a favour by weeding those people out in interviews.

Would you mind letting your hackles back down now?

Your question is hardly going to establish compentancy. What is going to do is the person on the other side is going to think what a twat.

If someone asks me shit like that in an interview i will be happy to not get the job cause clearly i am going to work with someone who thinks his a god ..... I already have that title.


if your interviewing a gradute knock your self out you will get a nice uni answer. If you interviewing someone like me .......... i will not apply for a job where the employer think your a graduate!

[jrandom]

What is going to do is the person on the other side is going to think what a twat.

Only if they can't actually answer the question, IME.

If someone asks me shit like that in an interview i will be happy to not get the job cause clearly i am going to work with someone who thinks his a god ...

Whatever works for you bro.