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Many people think that most developers don't actually need CS (and much less math) fundamentals in their every-day work life. That's why coding interviews like

Many people think that most developers don't actually need CS (and much less math) fundamentals in their every-day work life. That's why coding interviews like big tech companies tend to do are controversial ("Why would an iOS developer need to able to balance a binary tree?"). Can you give some examples where you hid road blocks because of your lack of education?

gopalv 9y ago
> Can you give some examples where you hid road blocks because of your lack of education? Not a veteran, but I've noticed something very odd about entry level jobs - they're not challenging. And that is no accident someone hiring you is actually doing that with a clear expectation that the complexity you're about to encounter will fit into their schedules. Higher education is very different - the professors are intentionally trying to push you, hopefully bit-by-bit out of the existing skill range into unknowns. At least mine weren't trying to teach me, they were trying to get me to learn, mostly by making my own stupid mistakes without a huge penalty attached to it. When I moved out of my CS course (and my open-source work building compilers) into my first job, the skill required to do my job satisfactorily was trivial. No more hard problems, just hard timelines. Took a couple of years and changing jobs before again landing up with a problem I didn't know how to solve ("Uh, make PHP5 fast ... Go!"), which helped me grow and learn. That was a lucky break, but I succeeded because my professors had pushed me into the deep end against my wishes (i.e more sleep) before.
tluyben2 9y ago
I benefit from my degrees but I would find it annoying if I would get asked questions like that. I design (among other things) crypto algorithms for banking purposes and implement them in a plethora of languages including ARM asm. But balancing a tree? I did that in an exam on paper 22 years or something ago. I would be able to do it given enough time but I probably would just walk out. 20 odd years ago when I was a cocky and already quite experienced coder, I would have done it easily but, although already having done many real life projects, I was a crap coder. And, due to the strangeness of the market and the scarcity back then, my current freelance salary in Europe, is not too different from what it was then. My feeling is still that those questions are pointless unless you want people straight out of uni. And then they already did their exams with those questions, so again pretty pointless...
aphextron 9y ago
>Can you give some examples where you hid road blocks because of your lack of education? At a certain point I was working on an iOS app attempting to do some really advanced animations with Core Animation/Core Graphics and my total lack of geometry and basic algebra knowledge started to show. One of my colleagues started talking about the movement of an animation in terms of radians and pi and I felt completely lost. He was speaking a totally different language to me. Up to that point I had felt somehow "proud" of being a self taught developer with no formal schooling. But when that happened I just felt completely embarrassed at my lack of fundamental knowledge and context. Now I'm struggling through undergrad mathematics classes and hoping to get to that point some day. The greatest overall takeaway I had from that experience is that math and science open a completely different world to you that most people don't even know exists. It changed my life.
- discreteevent 9y ago
  Good to hear that you are learning some practical applied mathematics. It will be useful. You might find that the mathematics taught as part of a CS course is much less useful for 90% of programming jobs and not much use in the rest of your life either.
- j_jochem 9y ago
  To be honest though, that stuff confuses the hell out of me too and I have an MSc in CS from a highly regarded German engineering university. So while I agree with your general sentiment about depth of knowledge, basic computer graphics linear algebra stuff is just another skill that you learn in a similar way to a new language, for example.
- taway_1212 9y ago
  A lot of the hardcore game developers (which use way more math and advanced CS concepts that most other devs) didn't go to college. This stuff is totally learnable on your own. I recommend for example "Essential mathematics for games" by Bishop and Van Verth.
  - jungletek 9y ago
gaius 9y ago
You do need to know there is such a thing as a b-tree, and when you might want one, and that balancing is a thing that you might want to do, and when to do it - even if you never actually implement one from scratch yourself, you absolutely do need the vocabulary to refer to it and a general understanding of the concept. That's what a lot of self-taught coders are missing - the knowledge of the theory that makes it easy to communicate with others.
dzonga 9y ago
clustering points on a map in iOS needs a good amount of data structures hint* Quad tree and a map like data structure
EduardoBautista 9y ago
You need it if you don't want to work on cookie cutter applications.
- Turing_Machine 9y ago
  I may need it, but I don't necessarily need to keep it in my head. That's why I own copies of Knuth, and Sedgewick, and Cormen, Leiserson, Rivest, and Stein. Now, the ability to understand and make intelligent use of those resources is something that requires education (formal or self). But oddly no one (that I've heard of) ever tests for that ability in job interviews.
- enraged_camel 9y ago
  Cookie-cutter isn't a bad thing. If it solves a real problem or addresses a real need, it will be successful. I mean Facebook started out as a cookie cutter app. Heck, it was a basic CRUD app. Look at where it is today. Outside of such unicorns there are also many examples of reasonably successful products that can be categorized as cookie-cutter. Basecamp. Trello. Snapchat. These apps don't do anything groundbreaking or operate on the bleeding edge of technology. But they are well-known and profitable.
  - redthrowaway 9y ago
    Cookie-cutter is also what 99% of programmers work on. Yes, it's nice that you were on the team at facebook that built the first react prototype, or that you were the first software engineer at oculus. The rest of us are building apps, adding an endpoint to an api, figuring out what the new database schema should look like, etc. And there are a hell of a lot more jobs openings for "blue-collar coders" than there are for geniuses. I mean, it's great you're working on the latest computer vision algo to make the billboards in Minority Report a reality. I just spent the day wrestling with Google's client API registration and authentication nonsense so I could get per-page bounce rates.
    - dba7dba 9y ago
      I agree. All of us outside of military hear about pilots and Navy SEAL at work most of the time. But 99% of men/women in military work doing none of that stuff. But that 99% are still gainfully employed doing essential work.
narribbi 9y ago
Balancing a binary tree is just an algorithm, like there are so many. As a programmer, you have to design algorithms on the fly, quite a few of which may actually be harder than just balancing a binary tree. Algorithms emerge automatically from designing data structures; when you end up manipulating these data structures. In turn, data structures emerge naturally from trying to model particular problems. There are too many branches in mathematics modeling too many types of problems than anybody could know them all. In that sense, asking a developer about how to balance a binary tree, is a dumb interview question. He should only know, if he happened to have worked on exactly that type of problem, only yesterday or so. The question is rather: If the following is the description of the algorithm to balance binary trees, show that you understand it by dealing with the details in the following examples.
- kkielhofner 9y ago
  Often times the right answer is (and should be) "show me you can find and use a use license-compatible library that typically has orders of magnitude more testing in the real world than something you feel the need to re-implement from scratch right now". The dirty secret is 90% of what happens in the real world (and on HN) is a solved problem that needs to be applied or re-applied. Someone has done it before and they've done it better than you will.
  - sirclueless 9y ago
    There's a difference between "I know how to do this but it would be a buggy mess and require a week or two of effort, therefore I shall use a library," and "I don't know how to do this but this library seems roughly applicable so maybe it will work." The former is a healthy and pragmatic use of your most valuable resource -- time. The latter is a cop-out. If no one actually understands what is going on at a deep level in the library, the result is likely to be an over-engineered mess. It might be that you're doing the most efficacious and appropriate thing for the task, but it might not. And with many such decisions made over the course of a project, some of them are bound to be wrong unless someone can reason about them and explain their purpose. I find this is most important when refactoring or updating code. Some junior engineer down the line will encounter some code he doesn't understand, and track down the guy who wrote it, and at this point there is a world of difference between that guy saying, "Yeah, we needed a data structure that does X and Y so we used that library," and "Uhhh, not sure why we used that library, does anything break if you remove it?"
Swizec 9y ago
I use my CS knowledge all the time when building webapps. Not directly of course, but as a general feel for things. Stuff like "Oh hey, this problem fits a state machine approach" and "I can reduce the complexity of this sprawling if statement by making a truth table and minifying stuff" And the good old "What you're asking for maps onto so and so problem and is fundamentally unsolvable. Can we tweak the requirements?" Sure, you're not inverting binary trees every day, but it's useful to be able to see where a binary tree would help you solve the problem.
- eropple 9y ago
  Agreed overall--I find that there's a real lack of appreciation of the sort of structural, high-level knowledge that I (at least) learned while getting a CS degree. And not a particularly good one, either, just something at a middling state school. Just being able to look at a problem and go "hey, this is pretty simple graph traversal, I know the rules for this" has saved my bacon. Or the type theory that I picked up along the way that made type-heavy programming in Scala and Rust make sense. Or the set theory (math, but required for my CS degree, so I count it) that does bounce through my brain when I'm thinking about databases. Or even, like--"hmm, I think I can bang out a quick and dirty parser," and knowing what that parser should look like because I've studied how programming languages work and I get that for free. I'm not the best programmer ever to walk the earth by a long shot, but I'm pretty good, and I'm pretty good because I can approach problems both bottom-up and top-down. Couldn't do both, flexibly, without a strong academic background.
eastWestMath 9y ago
Web developers who churn out crud apps think that.
fictioncircle 9y ago
They are controversial because they frequently don't let you look anything up and most developers are used to being able to do that as part of their normal process.
- nkozyra 9y ago
  The actual algorithm is irrelevant, so looking it up wouldn't be helpful. The point is to find out if the developer understands complexity well enough that they won't build bad things, that they'll know how to avoid nested loop if they can, that they'll know what the cost of one approach is compared to another. If you look something up and the interviewer asks you what the O() of your approach is and you don't know, how can they feel assured you grasp these fundamentals? I understand why these are contentious, but I find people tend to miss the forest for the trees when criticizing the practice.
  - fictioncircle 9y ago
    > The actual algorithm is irrelevant, so looking it up wouldn't be helpful. It isn't irrelevant if you are attempting to implement it correctly. > If you look something up and the interviewer asks you what the O() of your approach is and you don't know, how can they feel assured you grasp these fundamentals? That wasn't the original question in the comment I responded to and your attempt to re-phrase it as X when it was a question related to a specific algorithm is disingenuous. > Why would an iOS developer need to able to balance a binary tree? --- <removed a bunch of RL-related stuff that is pointless bitching about ppl we've fired>
    - nkozyra 9y ago
      > It isn't irrelevant if you are attempting to implement it correctly. Exactly my point. Rarely is there one "correct" implementation. Understanding the choice you make and can support is the point of coding interviews. That's why they're so often done in pseudocode and/or on the whiteboard. If you can look stuff up you're not demonstrating a knowledge of the fundamentals. If you don't understand complexity and optimization, you will make mistakes even if you can look stuff up later. That's why these companies do these.
crdoconnor 9y ago
Weirdly they seem to ask the CS fundamentals that aren't as relevant (algorithms) and skip those that are (e.g. the relational model, data structures (uses of), type theory, formal grammar). I wouldn't say that you don't need it, but I would say that most companies ask about the wrong bits.
- taneq 9y ago
  It always baffles me when people say that algorithms aren't relevant to software development. It's like saying thermodynamics isn't relevant to engine design.
  - JamesBarney 9y ago
    It doesn't seem that baffling to me. The majority of software applications could only moderately be improved by CS algorithms.
  - crdoconnor 9y ago
    More like saying that knowing the atomic crystalline structures of metals isn't relevant to engine design.
    - sirclueless 9y ago
      Well, somebody better know the structure of the metals in use, or else you get turbine disks shattering jet engines and landing 1,000 yards away [1]. Just because it's not important to know every day doesn't mean you won't find challenging and important applications of undergraduate-level algorithm design. [1]: http://www.seattletimes.com/business/boeing-aerospace/dramatic-ge-engine-explosion-on-boeing-767-poses-puzzle-for-investigators/ http://www.seattletimes.com/business/boeing-aerospace/dramat...
      - crdoconnor 9y ago
        "Well, somebody better know the structure of the metals in use" Somebody needs to know how to implement sorting algorithms too. It's just highly unlikely to be you.

gopalv 9y ago

> Can you give some examples where you hid road blocks because of your lack of education? Not a veteran, but I've noticed something very odd about entry level jobs - they're not challenging. And that is no accident someone hiring you is actually doing that with a clear expectation that the complexity you're about to encounter will fit into their schedules. Higher education is very different - the professors are intentionally trying to push you, hopefully bit-by-bit out of the existing skill range into unknowns. At least mine weren't trying to teach me, they were trying to get me to learn, mostly by making my own stupid mistakes without a huge penalty attached to it. When I moved out of my CS course (and my open-source work building compilers) into my first job, the skill required to do my job satisfactorily was trivial. No more hard problems, just hard timelines. Took a couple of years and changing jobs before again landing up with a problem I didn't know how to solve ("Uh, make PHP5 fast ... Go!"), which helped me grow and learn. That was a lucky break, but I succeeded because my professors had pushed me into the deep end against my wishes (i.e more sleep) before.

tluyben2 9y ago

I benefit from my degrees but I would find it annoying if I would get asked questions like that. I design (among other things) crypto algorithms for banking purposes and implement them in a plethora of languages including ARM asm. But balancing a tree? I did that in an exam on paper 22 years or something ago. I would be able to do it given enough time but I probably would just walk out. 20 odd years ago when I was a cocky and already quite experienced coder, I would have done it easily but, although already having done many real life projects, I was a crap coder. And, due to the strangeness of the market and the scarcity back then, my current freelance salary in Europe, is not too different from what it was then. My feeling is still that those questions are pointless unless you want people straight out of uni. And then they already did their exams with those questions, so again pretty pointless...

aphextron 9y ago

>Can you give some examples where you hid road blocks because of your lack of education? At a certain point I was working on an iOS app attempting to do some really advanced animations with Core Animation/Core Graphics and my total lack of geometry and basic algebra knowledge started to show. One of my colleagues started talking about the movement of an animation in terms of radians and pi and I felt completely lost. He was speaking a totally different language to me. Up to that point I had felt somehow "proud" of being a self taught developer with no formal schooling. But when that happened I just felt completely embarrassed at my lack of fundamental knowledge and context. Now I'm struggling through undergrad mathematics classes and hoping to get to that point some day. The greatest overall takeaway I had from that experience is that math and science open a completely different world to you that most people don't even know exists. It changed my life.

discreteevent 9y ago
Good to hear that you are learning some practical applied mathematics. It will be useful. You might find that the mathematics taught as part of a CS course is much less useful for 90% of programming jobs and not much use in the rest of your life either.
j_jochem 9y ago
To be honest though, that stuff confuses the hell out of me too and I have an MSc in CS from a highly regarded German engineering university. So while I agree with your general sentiment about depth of knowledge, basic computer graphics linear algebra stuff is just another skill that you learn in a similar way to a new language, for example.
taway_1212 9y ago
A lot of the hardcore game developers (which use way more math and advanced CS concepts that most other devs) didn't go to college. This stuff is totally learnable on your own. I recommend for example "Essential mathematics for games" by Bishop and Van Verth.
- jungletek 9y ago

gaius 9y ago

You do need to know there is such a thing as a b-tree, and when you might want one, and that balancing is a thing that you might want to do, and when to do it - even if you never actually implement one from scratch yourself, you absolutely do need the vocabulary to refer to it and a general understanding of the concept. That's what a lot of self-taught coders are missing - the knowledge of the theory that makes it easy to communicate with others.

dzonga 9y ago

clustering points on a map in iOS needs a good amount of data structures hint* Quad tree and a map like data structure

EduardoBautista 9y ago

You need it if you don't want to work on cookie cutter applications.

Turing_Machine 9y ago
I may need it, but I don't necessarily need to keep it in my head. That's why I own copies of Knuth, and Sedgewick, and Cormen, Leiserson, Rivest, and Stein. Now, the ability to understand and make intelligent use of those resources is something that requires education (formal or self). But oddly no one (that I've heard of) ever tests for that ability in job interviews.
enraged_camel 9y ago
Cookie-cutter isn't a bad thing. If it solves a real problem or addresses a real need, it will be successful. I mean Facebook started out as a cookie cutter app. Heck, it was a basic CRUD app. Look at where it is today. Outside of such unicorns there are also many examples of reasonably successful products that can be categorized as cookie-cutter. Basecamp. Trello. Snapchat. These apps don't do anything groundbreaking or operate on the bleeding edge of technology. But they are well-known and profitable.
- redthrowaway 9y ago
  Cookie-cutter is also what 99% of programmers work on. Yes, it's nice that you were on the team at facebook that built the first react prototype, or that you were the first software engineer at oculus. The rest of us are building apps, adding an endpoint to an api, figuring out what the new database schema should look like, etc. And there are a hell of a lot more jobs openings for "blue-collar coders" than there are for geniuses. I mean, it's great you're working on the latest computer vision algo to make the billboards in Minority Report a reality. I just spent the day wrestling with Google's client API registration and authentication nonsense so I could get per-page bounce rates.
  - dba7dba 9y ago
    I agree. All of us outside of military hear about pilots and Navy SEAL at work most of the time. But 99% of men/women in military work doing none of that stuff. But that 99% are still gainfully employed doing essential work.

narribbi 9y ago

Balancing a binary tree is just an algorithm, like there are so many. As a programmer, you have to design algorithms on the fly, quite a few of which may actually be harder than just balancing a binary tree. Algorithms emerge automatically from designing data structures; when you end up manipulating these data structures. In turn, data structures emerge naturally from trying to model particular problems. There are too many branches in mathematics modeling too many types of problems than anybody could know them all. In that sense, asking a developer about how to balance a binary tree, is a dumb interview question. He should only know, if he happened to have worked on exactly that type of problem, only yesterday or so. The question is rather: If the following is the description of the algorithm to balance binary trees, show that you understand it by dealing with the details in the following examples.

kkielhofner 9y ago
Often times the right answer is (and should be) "show me you can find and use a use license-compatible library that typically has orders of magnitude more testing in the real world than something you feel the need to re-implement from scratch right now". The dirty secret is 90% of what happens in the real world (and on HN) is a solved problem that needs to be applied or re-applied. Someone has done it before and they've done it better than you will.
- sirclueless 9y ago
  There's a difference between "I know how to do this but it would be a buggy mess and require a week or two of effort, therefore I shall use a library," and "I don't know how to do this but this library seems roughly applicable so maybe it will work." The former is a healthy and pragmatic use of your most valuable resource -- time. The latter is a cop-out. If no one actually understands what is going on at a deep level in the library, the result is likely to be an over-engineered mess. It might be that you're doing the most efficacious and appropriate thing for the task, but it might not. And with many such decisions made over the course of a project, some of them are bound to be wrong unless someone can reason about them and explain their purpose. I find this is most important when refactoring or updating code. Some junior engineer down the line will encounter some code he doesn't understand, and track down the guy who wrote it, and at this point there is a world of difference between that guy saying, "Yeah, we needed a data structure that does X and Y so we used that library," and "Uhhh, not sure why we used that library, does anything break if you remove it?"

Swizec 9y ago

I use my CS knowledge all the time when building webapps. Not directly of course, but as a general feel for things. Stuff like "Oh hey, this problem fits a state machine approach" and "I can reduce the complexity of this sprawling if statement by making a truth table and minifying stuff" And the good old "What you're asking for maps onto so and so problem and is fundamentally unsolvable. Can we tweak the requirements?" Sure, you're not inverting binary trees every day, but it's useful to be able to see where a binary tree would help you solve the problem.

eropple 9y ago
Agreed overall--I find that there's a real lack of appreciation of the sort of structural, high-level knowledge that I (at least) learned while getting a CS degree. And not a particularly good one, either, just something at a middling state school. Just being able to look at a problem and go "hey, this is pretty simple graph traversal, I know the rules for this" has saved my bacon. Or the type theory that I picked up along the way that made type-heavy programming in Scala and Rust make sense. Or the set theory (math, but required for my CS degree, so I count it) that does bounce through my brain when I'm thinking about databases. Or even, like--"hmm, I think I can bang out a quick and dirty parser," and knowing what that parser should look like because I've studied how programming languages work and I get that for free. I'm not the best programmer ever to walk the earth by a long shot, but I'm pretty good, and I'm pretty good because I can approach problems both bottom-up and top-down. Couldn't do both, flexibly, without a strong academic background.

eastWestMath 9y ago

Web developers who churn out crud apps think that.

fictioncircle 9y ago

They are controversial because they frequently don't let you look anything up and most developers are used to being able to do that as part of their normal process.

nkozyra 9y ago
The actual algorithm is irrelevant, so looking it up wouldn't be helpful. The point is to find out if the developer understands complexity well enough that they won't build bad things, that they'll know how to avoid nested loop if they can, that they'll know what the cost of one approach is compared to another. If you look something up and the interviewer asks you what the O() of your approach is and you don't know, how can they feel assured you grasp these fundamentals? I understand why these are contentious, but I find people tend to miss the forest for the trees when criticizing the practice.
- fictioncircle 9y ago
  > The actual algorithm is irrelevant, so looking it up wouldn't be helpful. It isn't irrelevant if you are attempting to implement it correctly. > If you look something up and the interviewer asks you what the O() of your approach is and you don't know, how can they feel assured you grasp these fundamentals? That wasn't the original question in the comment I responded to and your attempt to re-phrase it as X when it was a question related to a specific algorithm is disingenuous. > Why would an iOS developer need to able to balance a binary tree? --- <removed a bunch of RL-related stuff that is pointless bitching about ppl we've fired>
  - nkozyra 9y ago
    > It isn't irrelevant if you are attempting to implement it correctly. Exactly my point. Rarely is there one "correct" implementation. Understanding the choice you make and can support is the point of coding interviews. That's why they're so often done in pseudocode and/or on the whiteboard. If you can look stuff up you're not demonstrating a knowledge of the fundamentals. If you don't understand complexity and optimization, you will make mistakes even if you can look stuff up later. That's why these companies do these.

crdoconnor 9y ago

Weirdly they seem to ask the CS fundamentals that aren't as relevant (algorithms) and skip those that are (e.g. the relational model, data structures (uses of), type theory, formal grammar). I wouldn't say that you don't need it, but I would say that most companies ask about the wrong bits.

taneq 9y ago
It always baffles me when people say that algorithms aren't relevant to software development. It's like saying thermodynamics isn't relevant to engine design.
- JamesBarney 9y ago
  It doesn't seem that baffling to me. The majority of software applications could only moderately be improved by CS algorithms.
- crdoconnor 9y ago
  More like saying that knowing the atomic crystalline structures of metals isn't relevant to engine design.
  - sirclueless 9y ago
    Well, somebody better know the structure of the metals in use, or else you get turbine disks shattering jet engines and landing 1,000 yards away [1]. Just because it's not important to know every day doesn't mean you won't find challenging and important applications of undergraduate-level algorithm design. [1]: http://www.seattletimes.com/business/boeing-aerospace/dramatic-ge-engine-explosion-on-boeing-767-poses-puzzle-for-investigators/ http://www.seattletimes.com/business/boeing-aerospace/dramat...
    - crdoconnor 9y ago
      "Well, somebody better know the structure of the metals in use" Somebody needs to know how to implement sorting algorithms too. It's just highly unlikely to be you.