How to speed up calculation of length of longest common substring?

Posted by eSKay on Stack Overflow See other posts from Stack Overflow or by eSKay
Published on 2010-04-25T21:19:26Z Indexed on 2010/04/25 21:23 UTC
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Filed under:

algorithm

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lcs

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dynamic-programming

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suffix-tree

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c++

I have two very large strings and I am trying to find out their Longest Common Substring.

One way is using suffix trees (supposed to have a very good complexity, though a complex implementation), and the another is the dynamic programming method (both are mentioned on the Wikipedia page linked above).

Using dynamic programming $alt text$

The problem is that the dynamic programming method has a huge running time (complexity is O(n*m), where n and m are lengths of the two strings).

What I want to know (before jumping to implement suffix trees): Is it possible to speed up the algorithm if I only want to know the length of the common substring (and not the common substring itself)?

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