Hi
L~R,
1 use List::AllUtils qw/sum/;
2 use Bit::Vector;
3
4 my $k = 2;
5
6 my @letters = split '',"ABCDE";
7 my $n = scalar(@letters);
8
9 my $vec = Bit::Vector->new($n);
10
11 while(!$vec->increment){
12 my $i = $vec->to_Bin; # current bitstring
13 my $s = sum(split '',$i); # sum up to find out how many bits a
+re lit
14
15 next unless ($s == $k); # just the ones with $k bits lit
16
17
18 my $str = # convert bitstring to string
19 join '',
20 map { $letters[$_] }
21 grep { $vec->contains($_); }
22 0..$n-1 ;
23
24 print "$s $i $str\n";
25 };
The seen and set_seen routines are incorporated in the check at line 15.
The output for this is:
2 00011 AB
2 00101 AC
2 00110 BC
2 01001 AD
2 01010 BD
2 01100 CD
2 10001 AE
2 10010 BE
2 10100 CE
2 11000 DE