[Haskell-cafe] Longest increasing subsequence
Ariel J. Birnbaum
valgarv at gmx.net
Thu Apr 10 20:25:24 EDT 2008
> liss = maximumBy length . filter ascending . concat . map inits . tails
Of course my solution is braindamaged since I skipped this bit of the
definition: [quote]Note that subsequence we are searching for is not
necessarily contiguous[/quote]. Like the article says, without this detail
the problem is quite trivial =P
Replace
concat . map inits . tails
with
foldr (\x xss -> xss ++ map (x:) xss) [[]]
for a correct (yet even more inefficient) solution.
I'd blame the mistake on the late hour, but it was even later when I
noticed... *shame*
--
Ariel J. Birnbaum
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