Many hard LeetCode problems are easy constraint problems • Hacker News Board

Re: Many hard LeetCode problems are easy constraint problems

#421

Post by efortis » Sat, Sep 13, 2025, 6:48 AM UTC

theendisney wrote: post #394

coins = [100,50,25,10,5,1] change = 1234; result = [0,0,0,0,0,0]; for(i=0:i coins[i]){ result[i]++; change-=coins[i]; } } //[12,0,1,1,4] Coudnt help myself sorry

me neither

  function coin_change(change) {
    const coins = [25, 10, 5, 1]
    for (const coin of coins) {
      const n = change / coin | 0
      change -= n * coin
      console.log(coin, n)
    }
  }

  coin_change(25+10+5+1)

Re: Many hard LeetCode problems are easy constraint problems

#422

Post by esseph » Sat, Sep 13, 2025, 6:57 AM UTC

aidenn0 wrote: post #379

eek2121 wrote: post #357

Earlier quoted context omitted.

Only if there is enough evidence. Yes, I can say that the inability to account for things like the ADA in the US can place an employer in hot water, however, since LC doesn't make those decisions, they are immune. The accountability is placed upon the employer. Don't hate the players or the game. Maybe just figure out how to fix it without harming everyone, be popular enough to make said idea into law, and get into a…

I never meant to imply that LC would be violating the law.

Good legal disclaimer!

Re: Many hard LeetCode problems are easy constraint problems

#423

Post by esseph » Sat, Sep 13, 2025, 7:03 AM UTC

Figs wrote: post #350

samiv wrote: post #167

Earlier quoted context omitted.

The LC interviews are like testing people how fast they can run 100m after practice, while the real job is a slow arduous never ending jog with multiple detours and stops along the way. But yeah that's the game you have to play now if you want the top $$$ at one of the SMEGMA companies. I wrote (for example) my 2D game engine from scratch (3rd party libs excluded) https://github.com/ensisoft/detonator but would not b…

> SMEGMA companies Microsoft, Google, Meta, Amazon, I'm guessing... but, what are the other two?

Lol :)

Re: Many hard LeetCode problems are easy constraint problems

#424

Post by ReptileMan » Sat, Sep 13, 2025, 7:05 AM UTC

kccqzy wrote: post #5

Great insight. But this is sadly not applicable to interviews. > It's easy to do in O(n^2) time, or if you are clever, you can do it in O(n). Or you could be not clever at all and just write it as a constraint problem This nails it. The point of these problems is to test your cleverness. That's it. Presenting a not-clever solution of using constraint solvers shows that you have experience and your breadth of knowledg…

I always prefer the "The Soviets used a pencil" type engineers. Simplicity is quite close to greatness.

Re: Many hard LeetCode problems are easy constraint problems

#425

Post by [deleted] » Sat, Sep 13, 2025, 7:25 AM UTC

galaxyLogic wrote: post #416

roncesvalles wrote: post #401

Earlier quoted context omitted.

>a candidate’s willingness to invest time and effort I guess it's a matter of opinion but my point is, this is probably the right metric. Arguably, the kind of people who shut up and play along with these stupid games because that's where the money is make better team players in large for-profit organizations than those who take a principled stance against ever touching Leetcode because their efforts wouldn't contrib…

Then what if the test was how well you play chess? That takes time to study to become good. But would it be a good metric for hiring programmers?

[deleted]

Re: Many hard LeetCode problems are easy constraint problems

#426

Post by pjmlp » Sat, Sep 13, 2025, 7:28 AM UTC

roncesvalles wrote: post #264

samiv wrote: post #167

Earlier quoted context omitted.

The LC interviews are like testing people how fast they can run 100m after practice, while the real job is a slow arduous never ending jog with multiple detours and stops along the way. But yeah that's the game you have to play now if you want the top $$$ at one of the SMEGMA companies. I wrote (for example) my 2D game engine from scratch (3rd party libs excluded) https://github.com/ensisoft/detonator but would not b…

>The LC interviews are like testing people how fast they can run 100m after practice Ah, but, the road to becoming good at Leetcode/100m sprint is: >a slow arduous never ending jog with multiple detours and stops along the way Hence Leetcode is a reasonably good test for the job. If it didn't actually work, it would've been discarded by companies long ago. Barring a few core library teams, companies don't really care…

Does it work though?

When I look at the messy Android code, Fuchsia's commercial failure, Dart being almost killed by politics, Go's marvellous design, WinUI/UWP catastrophical failure, how C++/CX got replaced with C++/WinRT, ongoing issues with macOS Tahoe,....

I am glad that apparently I am not good enough for such projects.

Re: Many hard LeetCode problems are easy constraint problems

#427

Post by ascorbic » Sat, Sep 13, 2025, 7:29 AM UTC

roncesvalles wrote: post #264

samiv wrote: post #167

Earlier quoted context omitted.

The LC interviews are like testing people how fast they can run 100m after practice, while the real job is a slow arduous never ending jog with multiple detours and stops along the way. But yeah that's the game you have to play now if you want the top $$$ at one of the SMEGMA companies. I wrote (for example) my 2D game engine from scratch (3rd party libs excluded) https://github.com/ensisoft/detonator but would not b…

>The LC interviews are like testing people how fast they can run 100m after practice Ah, but, the road to becoming good at Leetcode/100m sprint is: >a slow arduous never ending jog with multiple detours and stops along the way Hence Leetcode is a reasonably good test for the job. If it didn't actually work, it would've been discarded by companies long ago. Barring a few core library teams, companies don't really care…

LC interviews were made popular by companies that were started by CS students because they like feeling that this stuff is important. They're also useful when you have massive numbers of applicants to sift through because they can be automated and are an objective-seeming way to discard loads of applicants.

Startups that wanted to emulate FAANGs then cargo-culted them, particularly if they were also founded by CS students or ex-FAANG (which describes a lot of them). Very, very few of these actually try any other way of hiring and compare them.

Being able to study hard and learn something well is certainly a great skill to have, but leetcode is a really poor one to choose. It's not a skill that you can acquire on the job, so it rules out anyone who doesn't have time to spend months studying something in their own time that's inherently not very useful. If they chose to test skills that are hard and take effort to learn, but are also relevant to the job, then they can also find people who are good at learning on the job, which is what they are actually looking for.

Re: Many hard LeetCode problems are easy constraint problems

#428

Post by pjmlp » Sat, Sep 13, 2025, 7:30 AM UTC

camdenreslink wrote: post #384

MarcelOlsz wrote: post #215

Earlier quoted context omitted.

There's an entire planet of jobs that have nothing to do with leetcode. I was talking about those, not FAANG stuff. Unfortunately I am not FAANG royalty. >Of course some still do, like Anthropic were you have to have a perfect score to 4 leetcode questions, automatically judged with no human contact, the worst kind of interview. Should be illegal honestly.

5 years ago non-FAANG companies were fully in leetcode mode for interviews. Maybe 10-15 years ago you could totally avoid it without much problem.

In most European companies that isn't a thing.

Thankfully not everything from SV culture gets adoption.

Re: Many hard LeetCode problems are easy constraint problems

#429

Post by qnleigh » Sat, Sep 13, 2025, 7:30 AM UTC

bluGill wrote: post #70

qnleigh wrote: post #36

Earlier quoted context omitted.

Yes, especially if the interviewee said something like 'this may not be asymptomatically optimal, but if it's not a known bottleneck, then I might start with constraint solver to get something working quickly and then profile later.' Especially if it's a case where even the brute-force solution is tricky. Otherwise penalizing interviewees for suggesting quick-and-dirty solutions reinforces bad habits. "Premature opti…

Using a bad algorithm when a good algorithm that is known to exist is premature pessimization and should be avoided. There is some debate about what premature optimization is, but I consider it about micro optimizations that often are doing things a modern compiler will do for you better than you can. All too often such attempts result in unreadable code that is slower because the optimizer would have done something…

> when a good algorithm that is known to exist

Sure, if a good algorithm exists and is simple to implement, then go for it. But if it is non-trivial, then you have to make a judgement call whether it is worth the trouble to solve in a more optimal way. You acknowledge yourself that that this can take days.

Personally I really have to be disciplined about choosing what to optimize vs what to code up quick-and-dirty. There's always a temptation to write clean, custom solutions because that's more interesting, but it's just not a good use of time for non-performance critical code.

Re: Many hard LeetCode problems are easy constraint problems

#430

Post by pendenthistory » Sat, Sep 13, 2025, 7:43 AM UTC

roncesvalles wrote: post #264

samiv wrote: post #167

Earlier quoted context omitted.

The LC interviews are like testing people how fast they can run 100m after practice, while the real job is a slow arduous never ending jog with multiple detours and stops along the way. But yeah that's the game you have to play now if you want the top $$$ at one of the SMEGMA companies. I wrote (for example) my 2D game engine from scratch (3rd party libs excluded) https://github.com/ensisoft/detonator but would not b…

>The LC interviews are like testing people how fast they can run 100m after practice Ah, but, the road to becoming good at Leetcode/100m sprint is: >a slow arduous never ending jog with multiple detours and stops along the way Hence Leetcode is a reasonably good test for the job. If it didn't actually work, it would've been discarded by companies long ago. Barring a few core library teams, companies don't really care…

It's also a filter for people who are ok with working hard on something completely pointless for many months in order to get a job.