On Sun, 29 Sep 2013 21:40:28 +0100, Henning Thielemann
<lemm...@henning-thielemann.de> wrote:
In Richard Bird's "Functional Pearls in Algorithm Design" there is
chapter 10 "Removing duplicates" which is about a fast and sorting
variant of 'nub'. After reading the introduction of the chapter I
answered mentally "Set.toAscList . Set.fromList - next chapter please".
However after the introduction eight pages follow that develop an
efficient algorithm for the problem. I suspected there might be the
additional difficulty of not using the standard Set type, however on
page 70 the common Set API is "imported". In the final remarks of the
chapter Bird writes: "A nagging doubt remains that there might be a much
simpler solution to such a simply stated problem. But so far I have not
been able to find one." Now I am lost. Can someone tell me, how the task
differs from what "Set.toAscList . Set.fromList" does?
It asks for the lexicographically least solution that is still an actual
subsequence, i.e. still in the order it appears in the input.
He gives the example that input "calculus" "aclus". Your way would
give "aclsu".
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