#!/usr/bin/perl
use warnings;
use strict;
use Data::Dumper;

for ([ qw(fooabc123 fooabc321 foobca232) ],
     [ qw(abcfoo123 bcafoo321 foo123abc) ],
     [ qw(foo bor boz bzo) ]) {

    print Dumper($_);
    print findlcs(@{ $_ }), "\n";
    print "---\n";
}

sub findlcs {
    my $substr = $_[0];
    my $len = length $_[0];
    my $off = 0;

    while ($substr) {
        my @matches = grep /\Q$substr/, @_;
        #printf "%s%-".(length($_[0])-$off)."s matches %d\n",
        #       " " x $off, $substr, scalar @matches;

        last if @matches == @_;

        $off++;
        $len-- and $off=0 if $off+$len > length $_[0];

        $substr = substr $_[0], $off, $len;
    }

    return $substr;
}