in reply to Re^3: Finding a LCS module on word level
in thread Finding a LCS module on word level

dragonchild,
I didn't review your logic other than to see you are using index. I am fairly certain that is a flawed approach since the OP is looking for the longest common substring based on words not characters. 
Have you ever seen the rain
I have never seen the rain

# should produce "seen the rain" not "ever seen the rain" because "eve
+r" ne "never"

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Cheers - L~R

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Re^5: Finding a LCS module on word level
by dragonchild (Archbishop) on May 10, 2008 at 02:58 UTC
    Good point. Leaving aside issues of "What constitutes a word", this process seems like it would boil down to: 
    sub lcs {
    my ($string, $find) = @_;

    $string = join ' ', split ' ', $string;
    my @f = split ' ', $find;

    my ($starting_point, $max_length, $substr) = (0,0, '');

    foreach my $start ( 0 .. $#f - 1 ) {
        foreach my $len ( 1 .. $#f - $start - 1 ) {
            my $search = join ' ', @f[$start .. $start + $len ];
            if ( $string =~ $search ) {
                if ( $len > $max_length ) {
                    $max_length = $len;
                    $start_point = $start;
                    $substr = $search;
                }
            }
        }
    }

    return $search;
}

    [download]
    My criteria for good software:
    1. Does it work?
    2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?
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