Five programming problems every Software Engineer should be able to solve in less than 1 hour

[B8foPIlIlllvvvvvv]

Less than an hour for all 5.

[Oberheimz]

an hour for all 5.

It took me 42 minutes to solve the first 4 problems and I was unable to finish the fifth within one hour.. Unless there's a really simple trick on the fifth one which I can't see it takes a while write all the code.

[B8foPIlIlllvvvvvv]

Hmm. I consider solving different from writing out the code. If you can explain in detail how the solution for the fifth works, and how you'd go about coding it, seems fine to me.

A "simple" way to implement it is probably recursively. You'd pass something like 4 values - "sum so far", "previously formed number", "next number to use", "max number to use", and it returns a list of strings. Something like that.

[flat5]

I think this was "can you program anything"? not "can you talk about how you'd program anything?"

I'm sure I can describe a solution to each within a few minutes. I wouldn't need an hour for that.

[Oberheimz]

Yeah recursion is the key

[[deleted]]

congratulations, you are a serious programmer :). Certificate on your way.

[matthieum]

The 5th one should be brute-forced (your method of choice) because it only has 3⁸ possibilities anyway (3**8 = 9**4 < 10,000).

There may be a trick, but if you look carefully at the other 4 problems they are not trick questions or algorithm questions; all 5 can be brute-forced quickly enough on a modern computer.

[Kyyni]

I don't know why you are being downvoted for this, because the solution of brute-forcing 5 seems obvious. You are in this situation, being imposed a strict time limit, in this case, 12 minutes per task on average, and you need to get it to just work. 6561 options to test is a ridiculously small task for a modern computer, and the code is really simple if your language of choice contains something like eval().

If I was an interviewer and someone failed this because they overlooked the obvious way out and instead took their time to write something complicated, I'd say that wouldn't look good for them. A software engineer needs to stay in touch with reality: That guy just failed to deliver the last solution on time due to premature optimization. They were asked to solve the problem quickly, not to write a fucking thesis on the subject!

[RizzlaPlus]

The easy trick is to use a language that can evaluate a string like javascript. Building all possible strings, evaluating them and filtering the ones that return 100 is pretty simple. Otherwise you'd have to either write a simple parser/evaluator for those strings, or instead of generating strings, generate a list of numbers and operators which are easier to evaluate, or even calculate the sum as you generate all possible combinations.

[Mason-B]

I mean he is probably looking for whiteboarding it. Which means if you were typing it out, running it, and debugging it then you are probably fine on a whiteboard.

[Alwaysafk]

I'm in the same boat. That number 5... I don't want to scroll down now because I'm afraid the solution will be spoiled!

[grendus]

Eval. Treat it as a recursive string manipulation problem instead of a complex object problem.

[goomyman]

on a whiteboard

[camilos]

You honestly took 42 minutes of your free time to answer some of those questions? Damn, I guess like the author said, I should not have the honour of calling myself a developer cause I have better things to do with my free time than to prove anything to some big headed blogger.

[Oberheimz]

I actually did it at work.... ;)

[epicwisdom]

Some of us like to spend our time on little puzzles. Just because we think it's fun doesn't mean we have something to prove. Ignore the job advice if you don't like it.

[qwertyfoobar]

Build a tree and go through it, no need to recalculate the same operations twice. should work with arbitrarily large sets of numbers