That really helps. Kind of like a lazy evaluating ST.

The problem remains O9n*n!), but for n-1 * n! passes the comp() comes down to 

    return $cache{$_[0]}{$_[1]} 
        if exists $cache{$_[0]}{$_[1]};

[download]

Which is a huge time saver (provided I don't run out of memory:).

Thanks.

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller
If I understand your problem, I can solve it! Of course, the same can be said for you.

In reply to Re: Re: Detecting transpositions by BrowserUk
in thread Detecting transpositions by BrowserUk

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