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Re: Re: Finding largest common subset in lists?

by anjiro (Beadle)
on Jun 06, 2003 at 04:34 UTC ( [id://263586]=note: print w/replies, xml ) Need Help??


in reply to Re: Finding largest common subset in lists?
in thread Finding largest common subset in lists?

So close! It works almost all the time, but this test case fails: 
my @a = qw( a b c d e f g h i j k l m n o p q r s t u v w x y z );
my @b = qw( a b c X f g h X l m n X j k a b c d );

[download]
Running on this, I get a b c as the result instead of a b c d. I'm looking to see if I can figure out why now, but I figured I'd post in case someone's faster than me (likely).

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Re: Re: Re: Finding largest common subset in lists?
by Jenda (Abbot) on Jun 06, 2003 at 09:32 UTC

    I'm stupid, stupid, stupid. There should be:

    ....
        if ($end > @result) {
            @result = @a[0..$end-1];
        }
...

    [download]
    instead of 
    ...
        if (--$end > @result) {
            @result = @a[0..$end];
        }
...

    [download]
    The way I have it I'd only update the @result if the newly found list was longer by at least 2 items. The usual off-by-one error :-(

    Jenda
    Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.
       -- Rick Osborne

    Edit by castaway: Closed small tag in signature

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