#! perl -slw
use strict;
use Data::Dump qw[ pp ];
use Algorithm::Combinatorics qw[ combinations ];

my @lines = map [ do{ chomp; split ',' } ], <DATA>;
my $w = $#{ $lines[0] };

my @keyFields;

WIDTH: for my $k ( 1 .. $w ) {
    my $iter = combinations( [ 0 .. $w ], $k );
    COMB: while( my $c = $iter->next ) {
        my %uniq;
        for my $a ( @lines ) {
            next COMB if exists $uniq{ join ',', @{ $a }[ @$c ] };
            $uniq{ join ',', @{ $a }[ @$c ] } = 1;
        }
        @keyFields = @$c;
        last WIDTH;
    }
}

print "All lines are unique using a combination of fields:[ @keyFields ]";

__DATA__
2,6,5,2,1,1,7,9,8,6
5,8,5,0,9,3,8,9,0,2
2,3,1,1,5,2,9,7,8,3
0,1,3,7,6,2,4,3,7,5
4,6,2,8,6,4,1,5,4,3
4,6,7,2,0,9,6,5,0,9
5,6,2,4,3,7,1,9,3,5
2,5,7,1,0,0,0,5,8,5
3,8,1,4,9,2,5,8,1,0
5,2,2,2,0,7,2,8,3,1
7,1,2,6,5,4,0,9,2,5
1,6,3,7,3,8,7,0,7,7
0,0,8,9,9,8,3,3,6,0
0,2,5,3,8,4,1,8,9,4
5,6,9,0,6,4,9,5,0,7
9,0,9,3,2,6,3,2,4,6
3,3,0,4,8,5,7,7,2,4
3,1,3,0,0,3,1,7,3,8
0,6,7,0,8,9,4,8,4,8
0,2,0,3,7,4,6,8,4,5