dev-haskell/lcs/metadata.xml


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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<herd>haskell</herd>
	<longdescription>
		Provides a function lcs that takes two lists and returns a longest
		common sublist. For example, lcs &quot;abcd&quot; &quot;acbd&quot; is either &quot;abd&quot; or
		&quot;acd&quot;.
		
		The package provides a simple, stupid and (most of all) slow
		implementation that needs, for inputs of length m and n, O(m+n)
		space and O((m+n)!) time in the worst case.
		
		It also provides an implementation of the Hunt-Szymanski LCS
		algorithm, based on that in &quot;String searching algorithms&quot; by
		Graham A Stephen, ISBN 981021829X.
		
		Given inputs xs and ys of length m and n respectively, where there
		are r pairs (x, y) where x is in xs, y is in ys and x == y,
		Hunt-Szymanski needs O(r+m+n) space and O((r+m+n)*log(m+n)) time.
		Thus this is O((m+n)^2) space and O((m+n)^2*log(m+n)) time in the
		worst case.
	</longdescription>
</pkgmetadata>