useful <https://github.com/flatland/useful> has a partition
function<https://github.com/flatland/useful/blob/develop/src/useful/seq.clj#L222>powerful
enough to make the "find increasing subsequences" part pretty easy:
(defn lis [coll]
(or (->> coll
(partition-between (partial apply >=))
(sort-by (comp - count))
(filter next)
(first))
[]))
This isn't much shorter than your approach, but it makes every step easy to
write and understand, and avoids doing any manual bookkeeping as in a
reduce. It doesn't help for 4clojure, obviously, since you don't have
partition-between available, but it underscores the importance of finding
common patterns and lifting them out into their own functions with
pluggable spots for the non-shared behavior.
On Tuesday, June 12, 2012 12:11:07 PM UTC-7, Andy C wrote:
>
> Hi,
>
> First a quick disclaimer. Those are my first steps in Clojure so I am
> not be super accustomed to the language entire landscape and might
> miss some basics here. However I was able to solve my first 4clojure
> hard problem https://www.4clojure.com/problem/53 and have some second
> thoughts after looking up top contributor's solutions as well as mine.
> Why it has to be so complicated???
>
> Conceptually, you just reduce the list to list of lists using a simple
> condition < . Then you filter items longer then 1. And at the same
> time you reduce the output to a first longest list. In this case,
> stack for recursion is really not required, although I did use it in
> my solution since I could figure out the "reduction" based way to
> partition the source sequence.
>
> It also seems that imperative solution would be quite straightforward
> although maintaining at least 4 state variables is not compelling at
> all. Bottom line, I want to have a idiomatic Clojure solution ... Any
> insight ....
>
> Thx,
> Andy
>
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