Programming Interviews

So in my job search I've learned something important - I'm really really really bad at programming tests and interviews. Actually, I'm pretty decent at standard algorithms/data structures-related questions that come up on phone screens, but I'm awful when it comes down to ironing out the details and dealing with edge cases. Just now I horribly failed a take-home test and I feel like total shit right now.

I realize I need more practice, and I've heard from a lot of people that TopCoder's practice rooms are a great way to do it.

Here's the problem:

I find the problems, even the lower-point ones, to be WAY too fucking hard. Is there a similar place with problems that are easier, or at least less math-heavy?

>>1
Mathematics is a religious pseudoscience. Failing at math isnt anything wrong, math just illogical and religious.

>>1
but I'm awful when it comes down to ironing out the details and dealing with edge cases.

Here is something during my code maintenance days at SUN Micro. You have to be OCD when it comes to details. In other words, being detailed about things almost has to become a fetish.

I find the problems, even the lower-point ones, to be WAY too fucking hard

You might want to consider taking up a different profession.

>>3
You have to be OCD when it comes to details. In other words, being detailed about things almost has to become a fetish.
Please, show us all the details about "Infinite Set".

>>3
OP here.
>You might want to consider taking up a different profession.
I've actually been working as a web developer for a year now since I've graduated.

I guess I was too mad to correctly say what I wanted to: the problems I've looked at have been hard, but I have a good idea about how to solve them. I've heard from other places (http://stackoverflow.com/questions/35901/interview-programming-test-practice/35906#35906) that the problems that are on TopCoder are harder than almost any interview question you will ever be asked.

VICTORY TO THE FARTISTS!

>>5
One of my favourites is to ask
What happens when you enter the following command at a Unix prompt: cp *
Isn't being accustomed with Unix pecularities was considered a bad programming feat at the times of true lispers, who wrote Unix Haters Handbook?

"cp *" is a good example of Worse is Better paradigm, where everything is inconsistent and can shot you in the leg.

You're a retard if you find mathematics hard, it is as simple and logical as it gets.

>>8
Please, show us all the details about "Infinite Set".

Here is a proof, that mathematics is inconsistent crap, that cant model observable reality:
http://en.wikipedia.org/wiki/Banach–Tarski_paradox

>>8
oh yeah fucker show P =/= NP

Learn how to suck the bosses' ego' penis. This is how most ``programmers'' succeed.

>>11
Too easy, as everyone assumes that that is already true. Prove P==NP.

>>12
everyone assumes
Yeah! "Assumption" is the meat of every religion.

>>13
Are you claiming that programming isn't the closest to God that it gets?

This literal idea of deus ex machina is almost too beautiful to be discussed here.

"God" could be interpreted monotheistically as the CPU (or polytheistically as a group of deities performing specific functions), governing all operations in the digital world, enforcing the rules. Or something more abstract, like the entire system or the physics, math and logic that drive it. Either way, it is a god invented by humans - just like the rest - to fulfill some need of theirs.

Does that make the programmer like a priest, pouring over tomes containing the ritualistic sequences of calls to the almighty system? Many programmers become more monastic than they'd like to believe, and certainly there are as many schools of thought about what the Right Way is.

These similes are shallow, so I stop here in hopes that someone else is responsible for going too far with the Lain-esque shit.

I am 12 apostle following and what is this

I believe in the duology of the great gods: apply and eval.

>>10
Mathematics cannot be inconsistent, but inconsistent axiomatic systems exist. Wether some specific set theories are consistent (and thus that specific geometric theorem is true) is an open question. If you're undecided about the consistency of some set theory (and thus that theorem), that's okay, but that doesn't mean the whole of math and logic is inconsistent (if they were, I doubt we'd even exist, or anything would physically exist at all), nor that we know about every conceivable mathematical structure. Also, since you're likely the ultrafinitist troll, I'll say this again: by denying natural numbers (the countably infinite), you're denying induction and various forms of computation. It may be that induction fails (as defined by Peano's Axioms), but I wouldn't assign that a (bayesian) probability larger than 10%. You seem to reserve any judgement on anything but that which you can personally observe, which is quite an irrealist position, and I should probably not argue with it as it's about as bad as solipsism.

Mathematics = axiomatic systems

>>18
by denying natural numbers (the countably infinite), you're denying induction and various forms of computation.
Yes. I'm, because computers, as finite state machine, are finite, so the computation is just an illusion, like "time".

>>20
this is just an illusion *grabs dick*

*grabs dubs*

>>19
Axiomatic systems can either be consistent or not. You can prove one system's inconsistency if you can prove a statement in that system is both true and false (starting from an axiom), that is, there is a contradiction. Of course, if you're using an unusual logic (such as one that doesn't follow the law of excluded middle), then the notion of inconsistency might not even make sense (an axiomatic system is defined in some logic, which itself follows some very simple axioms). A system which is stronger than peano arithmetic (and contains a part of it) cannot prove its own consistency, although its consistency may be provable in a stronger system (for example PA is consistent within some set theories, which themselves may or may not be consistent (for example proof by transfinite induction), however even if those systems were shown to be inconsistent (no such proof is known for modern set theories), it would still not show PA inconsistent). Either way, the concept of induction (and PA) seems sound and you could verify it as far as physical law allows if you wanted (that is up to any finite number), however I don't see any problem with claiming it is true for any finite number, and not just those which we can construct physically.

>>20
Illusion doesn't mean it doesn't exist. It just means it's a complex phenomena which is not fundamental. I should also mention that time is required for consciousness, but then denying consciousness isn't hard if you only look at it from the third person perspective and refuse to acknowledge the first person perspective.

>>23
To prove one system, you need another system, which will be subjective. Mathematics is subjective religion, based on circular reasoning, thay call "infinity".

>>24
Nope. I propose the reverse - that everything is subjective, which opossite to mathematics, that proposes existence of some eternal and all encopasing truths.

Dont respond to the "set theory hater" guy. Hes a sad autistic jew that hates anything that has to do with infinity.

Hey mr.jew, if infinity is not real, please tell me which is the largest number that exists?

>>25
To prove one system, you need another system, which will be subjective.
Yes, but you can get it down to universal computation which can be defined in very simple ways (and in many machines/languages which can be shown to be capable of implementing (or being
translated between) each other).

Mathematics is subjective religion, based on circular reasoning, thay call "infinity".
For a religion, it's the most exact one there can ever be, and it doesn't demand much, if anything.
It doesn't tell you to believe something is absolutely true, it just tells you that if you follow some specific rules, you'll get some specific results. For example, "if PA then ``various arithmetical theorems", "if ZFC then ``more theorems, but some could be like "PA and RA are true"''". Wether you think PA or ZFC is true is another thing, but it doesn't force you to believe in anything, it just tells you to apply the rules you defined and see what follows from them. As a religious statement (provably unprovable), I think PA is likely true (~90%) as the principles that it's based upon seem sound to me, and if for example you were to define a finite variant of it, you'd find it sound, now all that I take on belief is that induction is a valid schema axiom and thus all finite systems derived from it (given some specific axiomatization) are true (of which there are countably infinite). Of course, nobody will force you to believe anything, merely admit that "if PA then <theorems of PA>". Of course mathematical systems are defined in some logics and some of them are trivial (although not for everybody, see constructivism/intuitionistic logic who can at times deny the law of excluded middle). I wouldn't call it 'circular reasoning', merely seeing a principle as true and using it to reason, if you think induction is false, then don't use it, but I'd like to see what you will use instead of it (or if you deny reasoning at all, then I can't help you with it). If you don't assume ANYTHING, reasoning is impossible.
Nope. I propose the reverse - that everything is subjective, which opossite to mathematics, that proposes existence of some eternal and all encopasing truths.
Depends on what you mean by subjective. It is the case that a lot of systems are unprovable, but they are sound and there doesn't seem to be any paradoxes within them, however just because we cannot prove a system's consistency within itself does not mean that there actually exist contradictions within the system, just that any such proof would be infinite and thus impossible for a finite system like ourselves to complete (unless we cheat and use a stronger system, but then we cannot prove the consistency of that system and so on).
I'm a mix between a platonist and a formalist: I think finite computation is absolute and universal, that is I "believe" the Church-Turing thesis, however at the same time you can embed/implement theorem provers and axiomatic systems in computation and thus these systems will be able to arrive at the same truths in any possible universe (which is complex enough to allow computation, which usually just means some very simple rules and some form of time/state transition. Lack of time would also mean lack of computation and lack of any form of consciousness in that system (so no self-aware beings capable of even thinking of math and computation)). I should also mention that PA can embed computation within itself rather easily, but then a lot of systems can. There is a point though: just because ZFC can be embedded in some computation running in PA, does not mean I 'believe' it is true ontologically (it might be, but I'm undecided about it), merely that if you follow its rules, you will arrive at some theorems(truths following from axioms). ZFC's infinities are due its inventors desire of allowing all finite objects (such as numbers) to be taken as a set, and then allowing taking sets of other sets and so on (as long as non-circular, otherwise you get naive set theory which is provably inconsistent by Russell's Paradox). I don't think it's wrong to actually generalize from "finite system up to a natural number k is provably true", then for any k, it's true (in which case you get a countable infinity of such systems).
If you accept computation, but want to make it subjective, does that mean you think that following a system of rules in a specific way will give you DIFFERENT results each time you follow them? That would mean everything is inconsistent (how would we even exist then?). For example by this logic it would mean: on a bad day 1+1=5, and on most days 1+1=2? Is that what you meant?
My other claim is that even if we cannot prove a system's consistency (only inconsistency can be proven), that doesn't mean the system is inconsistent.

>>27
Yes, but you can get it down to universal computation which can be defined in very simple ways
"Simple" != meaningful.

For a religion, it's the most exact one there can ever be, and it doesn't demand much, if anything.
Yep! It can even prove itself to be a religion!
http://en.wikipedia.org/wiki/Gödel's_incompleteness_theorems

it just tells you that if you follow some specific rules, you'll get some specific results.
Meaningless rules lead to meaningless results.

Depends on what you mean by subjective.
By "subjective" I mean what I myself see and just that.


just because we cannot prove a system's consistency within itself does not mean that there actually exist contradictions within the system
even if we cannot prove a system's consistency (only inconsistency can be proven), that doesn't mean the system is inconsistent.
A false theory is false, even if not halted by a contradiction. -- L. E. J. Brouwer


Lack of time would also mean lack of computation and lack of any form of consciousness in that system (so no self-aware beings capable of even thinking of math and computation)).
What is "consciousness"? You are a little cranky, because official science hasnt answered this question today.

"Simple" != meaningful.
What is this meaning anyways? I don't even think 'meaning' means anything. For humans it's just association between a huge tree/graph of self-referential concepts. For axiomatic systems, it's just true statements within them.
By "subjective" I mean what I myself see and just that.
But you can verify an axiomatic system by running a theorem prover in a computational device, and you can observe the results if you wish.
A false theory is false, even if not halted by a contradiction. -- L. E. J. Brouwer
That quote seems to only return results from your posts and some russian forum. I don't know what "false" even means in that case. For me the word inconsistent just means "no contradiction". Real world meaning of 'false' just means that something is not of the value that is claimed (for example: "the keys are in the pocket" is false if the keys are not in the pocket").
What is "consciousness"? You are a little cranky, because official science hasnt answered this question today.
Science can't answer that question since consciousness either doesn't exist or it exists, but has no causal properties (some form of epiphenomenalism). For me, it's just the unique way I perceive my own internal state, nothing else.

Also, when I said consciousness cannot exist without time, I also meant it in the way that we wouldn't have evolved, we as physical systems wouldn't have existed, nor would have our brains have existed and thus neither the internal states and apparent computation that is going on would exist. Internally we record how physical states evolve over time by updating our memories (changes in synapses and brain chemistry), we "perceive" such change internally as some form of phenomenal experience. No time = no experience/consciousness.

>>29
What is this meaning anyways? I don't even think 'meaning' means anything. For humans it's just association between a huge tree/graph of self-referential concepts. For axiomatic systems, it's just true statements within them.
If you do meaningless things and be an autist, evolution will clean you and genes from population.

But you can verify an axiomatic system by running a theorem prover in a computational device, and you can observe the results if you wish.
Why should I? What would be the meaning of those actions?

That quote seems to only return results from your posts and some russian forum.
Please, learn to use search engines.
http://www.infinite-beyond.com/scripts/kaplan_theartoftheinfinitethepleasuresofmath.pdf

>I also meant it in the way that we wouldn't have evolved, we as physical systems wouldn't have existed, nor would have our brains have existed and thus neither the internal states and apparent computation that is going on would exist.
The factorial of 9999999999999999999999 is constant. There are no computation. The program can be expanded.

I enjoy coming here and watching /prog/ sage questions about programming and then ramble on for 30 posts about math as religion.

>>31
If you do meaningless things and be an autist, evolution will clean you and genes from population.
We were talking about different things. Meaning that I was talking about is about the descriptive equivalence between things. Meaning that you're now talking about is about what is evolutionarily good/leads to survival.
Why should I? What would be the meaning of those actions?
If you're really going to talk about usefulness here, math is quite useful in engineering and physics and more general computation (such as what you do on a computer).
The factorial of 9999999999999999999999 is constant. There are no computation. The program can be expanded.
I'd figure an ultrafinitist like you would ignore such large numbers. Yes, it's a constant, but reaching the exact value of that constant (that is, evaluating 9999999999999999999999!) requires a process (which can be a computation), the fact that the factorial equals to some constant is clear, but what the constant is cannot be reached except by computation (mathematical proof, that is, following a finite number of steps by applying some rules to find the literal value is also a computation, despite that the equality between 9999999999999999999999! and its literal value cannot be disputed).

http://www.infinite-beyond.com/scripts/kaplan_theartoftheinfinitethepleasuresofmath.pdf
Now that I know what the context is, it seems it talks about some axiomatic system's ontological existence. That is indeed a valid question. Personally, I assign a higher than 50% probability for the existence (truth) of arithmetic (thus all finite computational systems). I'm undecided by iterative set theories for now, but my belief in arithmetic seems to imply that infinity at least up to Aleph Null (ℵ₀) exists. Wether 2^ℵ₀ or higher infinities exists depends on wether various set theories make sense, hence I'm undecided about the existence/truth of real numbers, the continuum or higher infinities, however as far as I've read about set theories, a belief in the lowest countable infinity can lead one to think certain set theories are sound and thus higher infinities must also exist, but at the same time, even for some particular set theory, you'll reach such a high infinity where you cannot even prove its existence in that particular set theory. A better way to talk about this would be http://en.wikipedia.org/wiki/Ordinal_analysis (a particular infinite axiomatic system is true if specific ordinals exist, that is, if you can perform transfinite induction up to that ordinal to show that the axiomatic system is a theorem of some particular set theory).

>>31
If you do meaningless things and be an autist, evolution will clean you and genes from population.
I'm betting this "autism" of modeling the abstract will be very useful to us in the long run (its been useful in giving us our technological civilization through science and engineering). You seem to be betting against it?

>>33
We were talking about different things. Meaning that I was talking about is about the descriptive equivalence between things.
Equivalence is meaningless, when are "abstract"

Meaning that you're now talking about is about what is evolutionarily good/leads to survival.
Ther no other meaning, besides that simple meaning supplied by the evolution, which looks very deterministic.

I'd figure an ultrafinitist like you would ignore such large numbers.
Yes. Because these numbers are meaningless and useless. You wont find them in actual programs or other engineering designs.

Personally, I assign a higher than 50% probability
What is "probability"? In practice I have seen only reational numbers in the form hits/total, which were called "probability". I dont see, were you got these default rationals for this "truth" of yours.

>>35
Equivalence is meaningless, when things are "abstract"
self fix.

>>34
Can you show us "Infinite Set"?

>>35
Different kind of probability here, I'm talking about my confidence in a particular theory given the evidence that I've observed:
http://en.wikipedia.org/wiki/Bayesian_probability
Yes. Because these numbers are meaningless and useless. You wont find them in actual programs or other engineering designs.
Really now? Have you actually looked at such designs or programs? A compiled program can be represented/encoded as a concrete number. As for engineering, do you think they don't rely very heavily on applied physics?
Ther no other meaning, besides that simple meaning supplied by the evolution, which looks very deterministic.
You're oversimplifying things and are missing the big picture here, and I'm too lazy to write more longposts describing it.
Equivalence is meaningless, when things are "abstract"
Only because of how you define "abstract" and "meaning". Your definition is different from other people's.
>>37
Do you mean enumerate or define? To define some infinite set is easy. To fully enumerate is impossible by definition. That doesn't mean that there isn't an infinity of natural numbers.

>>38
I'm talking about my confidence in a particular theory given the evidence that I've observed:
How do you know, when evidence supports your belief?

Do you mean enumerate or define? To define some infinite set is easy. To fully enumerate is impossible by definition. That doesn't mean that there isn't an infinity of natural numbers.
I mean physically showing an object, description of which would require the concept of "Infinite Set".

As for engineering, do you think they don't rely very heavily on applied physics?
I dont think about the things I havent seen. I'm not a religious person and have no imagination.

You're oversimplifying things and are missing the big picture here, and I'm too lazy to write more longposts describing it.
Your answer shows that you're out of viable arguments. I will interpret it as your surrender.

>>39
How do you know, when evidence supports your belief?
Evidence = fact. If observations match expectations (observations can be things coming from the senses, but they can also be fully abstract thoughts and proofs which can be verified from premises to conclusion). I also have other heuristics about how I'm selecting my beliefs: Occam's razor is a general principle which I use (and its mathematical and computational variants). The reason why Occam's razor is a good heuristic is easy enough to show using probability theory (http://lesswrong.com/lw/jk/burdensome_details/ http://lesswrong.com/lw/jp/occams_razor/)
Your answer shows that you're out of viable arguments. I will interpret it as your surrender.
Partially, I just can't find the interest to continue the discussion.
I dont think about the things I havent seen. I'm not a religious person and have no imagination.
If I'm to take the term 'religious' to mean having 'provably unprovable' beliefs (not in the sense of believing in some popular religion). In that sense, I think most people are religious (including myself, despite being effectively atheist), we all have some initial/a priori beliefs, examples could be:'I exist', 'I am thinking', 'Mathematical induction is a sound principle', 'There is a reality and I'm embedded in it' and so on. If you refuse to hold any, you cannot do any kind of thinking and lose any advantages you have over other animals. Even if you deny having some beliefs, your brain/mind has a lot of them, many which you don't even realize exist, although some which you could discover by introspection. The use of term 'belief' is just about internal expectations about the behavior of other systems. Abstract beliefs may be expectations about things which may not be obviously connected to reality as observed by one's senses. A "religious" (a priori) statement of mine would be that whatever my senses are capturing comes from such an abstract structure which I internally call 'the universe' and this structure has a consistent mathematical description, which is why for me the abstract and the experiential are closely connected and it is not pointless to think about them (not that this means I think a particular set theory is true or not, I'm mostly undecided about such axiomatic systems, although I'm inclined to believe arithmetic to be likely true at least, as if it was false, Church-Turing thesis would be false(what?) and some definitions of computation would be impossible). There's some other stuff that I would like to say, but it would take too long and since you yourself claimed to have no imagination and don't like to think of about abstract things, I'll refrain from posting about them (not to mention I have other things to do now and don't feel like wasting my time on a conversation about something which the other party doesn't seem to be interested in).