hackageDB :: [Package]

lcs: Find longest common sublist of two lists

Provides a function lcs that takes two lists and returns a longest common sublist. For example, lcs abcd acbd is either abd or acd.

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 String searching algorithms 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.

Modules

• Data
  • List
    • Data.List.LCS
      • Data.List.LCS.HuntSzymanski
      • Data.List.LCS.Simple

Downloads

• lcs-0.2.tar.gz (Cabal source package)
• package description (included in the package)