Interesting but lesser known data structures • Hacker News Board

Re: Interesting but lesser known data structures

#21

Post by silentbicycle » Thu, Mar 24, 2011, 4:11 PM UTC

SeanDav wrote: post #7

SeanDav wrote: post #2

Not sure one could call it a data structure but who remembers the so-called Sneaker Network or Tackie Network, which consisted of someone copying information onto a disk and physically walking to the other machine to copy the information. Networks were so slow/buggy that it was often quicker to transmit information using this "data structure"

Yes the Floppy disk is the Data Structure, which is interesting in itself, but in order for this data structure to work it must be both loosely and tightly coupled to the transport layer.... edit: To the downvoters - is a sense of humour not allowed on HN?

If you're going to try to be funny, at least include it as part of an otherwise worthwhile comment, otherwise it just adds noise to the discussion (and encourages more of same). I know HN seems kind of neurotic about this, but we're trying really hard to keep away trite "first post", "[citation needed]", etc. comments, and given HN's age, it actually seems to work.

Re: Interesting but lesser known data structures

#22

Post by Silhouette » Thu, Mar 24, 2011, 6:39 PM UTC

ominous_prime wrote: post #8

I feel like there isn't a good excuse for programmers to not know about a lot of these structures. Yes, some of the examples are somewhat unknown (I didn't know about the 2008 paper on "Left-Leaning Red-Black Trees" for example), but many of these are something that would be at least mentioned in basic college algorithms or data-structures courses. (I have a feeling the voting is skewing my perception, and people are…

I think perhaps you are looking at basic college data structures courses through rose-tinted glasses.

A typical first course in data structures is where novice students learn about everyday tools like hash tables and balanced binary trees. It probably mentions a few slightly more amibitous things, but not many.

I would hope a second course at least introduced topics like purely functional and lock-free data structures and their applications, but obviously you're not going to get Okasaki and everything that's developed since at that level.

Most people doing a straightforward CS/SE degree aren't going to do a lot more than two general data structures courses, and maybe encounter a few of the more specialist tools in applied courses on topics like 3D graphics or databases/information storage.

Re: Interesting but lesser known data structures

#23

Post by T-R » Thu, Mar 24, 2011, 10:39 PM UTC

EMRo wrote: post #19

Noob question: I hacked together my little mobile website and am looking to cut down on search time for a "similar search" I built. Short Description: Each "unit" has x attributes in the form of strings (tags). Searching queries a database using a standard mysql regexp search for each tag across all "units" and sorts responses by # of tags matching Desc. I know this isn't StackOverflow so this isn't really a tech que…

You probably got downvoted for being off-topic - it'd be better to ask that kind of question on Stack Overflow. Leave out the subjective "is it because I'm a noob?" parts, and stick with the more objective "is there a better way to do this?", and you'll probably be able to figure out from that where any holes in your knowledge/experience might be.

Re: Interesting but lesser known data structures

#24

Post by cpeterso » Fri, Mar 25, 2011, 6:16 AM UTC

Trey-Jackson wrote: post #11

ominous_prime wrote: post #8

I feel like there isn't a good excuse for programmers to not know about a lot of these structures. Yes, some of the examples are somewhat unknown (I didn't know about the 2008 paper on "Left-Leaning Red-Black Trees" for example), but many of these are something that would be at least mentioned in basic college algorithms or data-structures courses. (I have a feeling the voting is skewing my perception, and people are…

IMO, 99.9% of the time you don't need the more obscure data structures. And I speak from experience working in companies on software requiring high performance (runs taking 6 hours to two days are not uncommon). That said, I was disappointed nobody had added the corner stitched data structure - I found that to be a very intriguing idea (and in my world, it turned out to be very useful).

I've heard someone joke that "real world" software uses just two data structures: arrays and hash tables.

1. An array can implement a stack or queue and is often cache-friendlier than a linked list of nodes scattered throughout the heap.

2. A hash table can implement a map or set for fast lookups of unordered data.

Re: Interesting but lesser known data structures

#25

Post by EMRo » Fri, Mar 25, 2011, 2:43 PM UTC

T-R wrote: post #23

EMRo wrote: post #19

Noob question: I hacked together my little mobile website and am looking to cut down on search time for a "similar search" I built. Short Description: Each "unit" has x attributes in the form of strings (tags). Searching queries a database using a standard mysql regexp search for each tag across all "units" and sorts responses by # of tags matching Desc. I know this isn't StackOverflow so this isn't really a tech que…

You probably got downvoted for being off-topic - it'd be better to ask that kind of question on Stack Overflow. Leave out the subjective "is it because I'm a noob?" parts, and stick with the more objective "is there a better way to do this?", and you'll probably be able to figure out from that where any holes in your knowledge/experience might be.

I appreciate the constructive response. I'm going to do that. Just joined this community so just learning the rules now. Thanks.