Update: fixed code to work with
zby's case and hopefully any other case.
Update: code won't work with duplicates in the second list
Not exactly vastly mystical but this should do the trick (although it hasn't been thoroughly tested)
use strict;
my @a = qw/ fred bob joe jim mary elaine /;
my @b = qw/ frank joe jim mary bob /;
print "LCS[anjiro] - ", join($", get_lcs(\@a, \@b)), $/;
@a = qw/ a b c /;
@b = qw/ a b x c /;
print "LCS[zby] - ", join($", get_lcs(\@a, \@b)), $/;
sub get_lcs {
my @a = @{ +shift };
my @b = @{ +shift };
my %map = map { $b[$_] => $_ } 0 .. $#b;
my(@lcs, @tmp);
for(0 .. $#a) {
next unless exists $map{$a[$_]}
or $a[$_ + 1] eq $b[$map{$a[$_]} + 1];
push @tmp, $a[$_] if $a[$_] eq $b[$map{$a[$_]}];
if($a[$_ + 1] ne $b[$map{$a[$_]} + 1]) {
@lcs = @tmp if @tmp > @lcs;
@tmp = ();
}
}
@lcs = @tmp if @tmp > @lcs;
return @lcs;
}
__output__
LCS[anjiro] - joe jim mary
LCS[zby] - a b
You might also find some roughly applicable questions under
Longest Common Substring.
HTH
_________
broquaint
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