#!/usr/bin/perl
## LONGEST COMMON SUBSTRINGS (sorted) from a set of given sequences:
use strict;
use warnings;
sub LCS {                             # Line 5 
    my ($ctx, $a, $b) = @_;
    my ($amin, $amax, $bmin, $bmax) = (0, $#$a, 0, $#$b);
    while ($amin <= $amax and $bmin <= $bmax and $a->[$amin] eq $b->[$bmin]) {
        $amin++;
        $bmin++;
    }
    while ($amin <= $amax and $bmin <= $bmax and $a->[$amax] eq $b->[$bmax]) {
        $amax--;
        $bmax--;
    }                                  # Line 15 
    my $h = $ctx->line_map(@$b[$bmin..$bmax]); # line numbers are off by $bmin
    return $amin + _core_loop($ctx, $a, $amin, $amax, $h) + ($#$a - $amax)
        unless wantarray;
    my @lcs = _core_loop($ctx,$a,$amin,$amax,$h);
    if ($bmin > 0) {                   # Line 20 
        $_->[1] += $bmin for @lcs; # correct line numbers
    }
    map([$_ => $_], 0 .. ($amin-1)),
        @lcs,
            map([$_ => ++$bmax], ($amax+1) .. $#$a);
    }
sub a {                                    
    my $match = CSS(@_);            # line 28 
    if ( ref $_[0] eq 'ARRAY' ) {
       @$match = map{$_->[0]}sort{$b->[1]<=>$a->[1]}map{[$_,scalar(@$_)]}@$match
    }
    else {                          # Line 32 
       @$match = map{$_->[0]}sort{$b->[1]<=>$a->[1]}map{[$_,length($_)]}@$match
    }
  return $match;
}
## Data Input & Results:                   # Line 37 
print"\nThe longest common substrings in decreasing order of lengths:\n";
my $result1=a qw(ABABC BABCA ABCBA);
my $leng1=$result1;                        # Line 40 
print"\n$result1; Length=$leng1\n\n";
exit;