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Comment by Jensson | Hacker News Reader

> It's at most a signal for whether or not they remember algorithms 101 or some leetcode exercise, but knowing that they do remember isn't really useful to me

For bubble sort? Do you really think anyone should have to remember an algorithm to write a quadratic time sort? All you have to do is "compare and swap" and loop through until you are done, this is way easier than Fizzbuzz.

This is only hard if you have a hard time grasping loops, conditional comparisons or swaps. But if you understand all of those the sort writes itself. And understanding loops, comparisons and swaps is pretty fundamental to anything you do as a software engineer, so I'm not sure how any competent software engineer could struggle with it.

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Every technical thing you know is informed by your practice in an area. There's a lot of roles where you don't even have to think about which algorithm is implemented behind your favorite sort method. If you work in a role like that for 10 years, bubble sort becomes "which one was that again"?

Engineering is about solving valuable problems. Solving some of those problems requires obsessive control over (and selection of) specific sorting algorithms, many do not.

Edit: it's also worth bearing in mind that many of the people who discovered these algorithms are famous in part for having thought them up. If data structures and algorithms were so obvious, nobody would know who many of these people were.

Assuming knowledge and understanding of an algorithm but no prior practice with implementing it, one’s way of implementing it does tell about their proficiency in programming.

GPs bubble sort was obviously just an example, effectiveness of the algorithm or wether there’s ever need for implementing it by hand is irrelevant.

> All you have to do is "compare and swap" and loop through until you are done, this is way easier than Fizzbuzz.

I think you have this wrong, Fizzbuzz is actually completely trivial to the point where the problem statement is almost literally (modulo modulo) a description of the algorithm.

Bubble sort is very easy but it's not literally trivial to the same degree as Fizzbuzz!

for i = 0 to n { for j = i to n { if n[j] > n[i] { swap(n[i], n[j] }}}

1 point for having a good reply. 100 points for doing it in code. Well done!

Except that sorts the list in reverse: https://tio.run/##Vc6xDsIwDATQPV9xYyJ5od2Qyo9UGYhIwFXkVlY68P...

(Also a subtle off-by-one error, it should be 0 to |n|-1 and i to |n|-1.)

Thanks for catching the reverse. I was aware of the off by one but thought the “to” operator I invented would be exclusive of the second operand (kinda like range in Python) :)

> Fizzbuzz is actually completely trivial to the point where the problem statement is almost literally (modulo modulo) a description of the algorithm.

Fizzbuzz requires you to read and understand a few lines of requirements. That is much harder than just "order these elements, runtime isn't important", you can easily miss some part of the problem statement or misunderstand it for Fizzbuzz and fail, you shouldn't but it can happen, no such thing for a quadratic sort.

>This is only hard if you have a hard time grasping loops, conditional comparisons or swaps

Or because you don't know the algorithm in question... The problem isn't bubble sort but any generic algorithms test. The examiner wants you to write code but not tell you the specification because it would be shockingly similar to telling you the solution.

When I read a post on HN about inverting a tree I was wondering how exactly you are supposed to invert the child and parent relationship so that children point to parents instead of parents pointing to children. I.e. leaf nodes are now at the root and the root node is where the leaf nodes are supposed to be. Then someone said "He meant reversing the tree" and I'm like "That is not what he said."

> Or because you don't know the algorithm in question

I don't think anyone would care if you did an insertion sort or some other brute force way to sort. Brute force sorting in general is trivial to come up with.

I agree with this.

You'll often see responses like "but many people don't need to write sorting algorithms from scratch in their day to day work, so they're out of practice". But to me this attitude itself is indicative of the issue.

Being able to do this doesn't require sorting algorithms to be well-practiced and fresh in one's mind. It requires a general ability to visualize and reason about simple data manipulations. Which to me is an absolute fundamental for a programmer working in any field.

If the algorithm can be described with a small sketch or a couple of sentences, generally an implementation should just flow for an experienced programmer who has general fluency? For something like bubble sort, the description can be more or less directly translated to code.

The fact that someone even conceives of this as something which needs to me memorized / practiced suggests to me that they might not have that kind of basic working fluency.

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