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Ask HN: What's the hardest problem you've ever solved?

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Re: Ask HN: What's the hardest problem you've ever solved?

#121

Post by catchmeifyoucan »

nscalf wrote: post #103
yholio wrote: post #90

I somehow decided I needed to cheat to pass a certain exam because I was basically crap at memorizing stuff. So I used an analogue wireless headphone, an induction loop around my neck and a mobile phone. Since I lacked an accomplice to dictate, I read aloud the hundreds of pages and recorded myself, careful to preserve and properly serialize things like complex formulas. This was before the era of iPods and SDCard pl…

I would 100% talk about this in interviews depending on the interviewer. I can think of a couple interviews I had in SF that would probably be appreciative of this level of effort because you principally reject memorization.

It adds a human component to your interview. As the saying goes, programmers are lazy. Based on the components you describe, I think it's safe to say, that you're not an entry-level hire and you have experience in your field. It'll make for a great story and demonstrates passion.

Re: Ask HN: What's the hardest problem you've ever solved?

#122

Post by rorykoehler »

Aeolun wrote: post #116
rorykoehler wrote: post #111

I solved a performance bug that was probably going to cost my company the majority of our customers if we didn't sort it out as it made the app unusable. It had been going on for months. None of the dev team had any idea. APM was throwing out a bunch of red herrings. I haven't written a line of code in the app or a line of production Java (the codebase language) in my life. In the end I tracked it down to a single li…

Sometimes selectively commenting stuff out really is the best way to figure out what is wrong.

I do this a lot but it wouldn't have helped in this case unfortunately. Also the code base is over 700k lines which added another parameter to the mix.

Re: Ask HN: What's the hardest problem you've ever solved?

#125

Post by CodeWriter23 »

Getting clean off drugs and alcohol.

Oh, and debugging a DOS TSR (Terminate and Stay Resident) API for realtime communications to mainframes and other information sources (async and X.25) while running under Windows 386 - Windows 3.11. Every different network stack (IPX, Netbeui, LanMan, etc.) presented a new brainfucker of a problem.

Re: Ask HN: What's the hardest problem you've ever solved?

#126

Post by dfox »

As far as CS goes the hardest problem I'd somehow "solved" involves designing program that produces reasonable approximations of optimal solutions for TSP/VRP. The actual implementation took a weekend of wall time (which includes several weeks of single-core CPU time), but that was preceded by two months of reading papers with abstracts like "We present practical approach to solving intractable problems".

Re: Ask HN: What's the hardest problem you've ever solved?

#128

Post by twtw »

jey wrote: post #112
amp108 wrote: post #106

Earlier quoted context omitted.

One thing universities should teach is efficient problem solving. If it was more work to cheat than to memorize, I'd say you might want to re-evaluate whether "not memorizing things" is a principle you should cling so dogmatically to.

I'm sure he learned much more useful stuff by coding up that monstrosity, and in the real world he can just google to look up those formulas he didn't memorize. The fully elaborated version of the underlying principle is probably something like: "I have much better ways to spend my time than on memorizing formulas that I could easily look up later".

If an individual's philosophy is that you can always google stuff so you don't need to know anything, I don't see why that person should waste time in school.

Re: Ask HN: What's the hardest problem you've ever solved?

#129

Post by twtw »

hn_throwaway_99 wrote: post #113
nscalf wrote: post #103

Earlier quoted context omitted.

I would 100% talk about this in interviews depending on the interviewer. I can think of a couple interviews I had in SF that would probably be appreciative of this level of effort because you principally reject memorization.

Admitting to significant academic fraud during a job interview is a very, very bad idea. Furthermore, I would question the ethics and morality of any company that said "Wow, you solved an incredibly tough problem in order to commit fraud. Boy, are we the place for you!"

Eh, probably some places (e.g. Uber) would love that kind of thing.

Re: Ask HN: What's the hardest problem you've ever solved?

#130

Post by TomVDB »

I had designed a PCI chip. Our driver team reported that the PC would hard hang under certain conditions. They suspected a bug in the chip.

Armed with a PCI analyzer, I figured out that it was a race condition where the firmware on the chip would raise an interrupt to the PC. And they would clear the interrupt right at the moment where the firmware wanted to issue a new interrupt.

If performed in the wrong order, the PCI interrupt stayed high even after the PC thought it was already serviced.

The solution was to just switch around 2 lines of code in the firmware, but it took two weeks to figure that out.

Not that long, but it was an insidiously subtle mistake.

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