Question

I’ve been challenged with a mathematics problem. Given ten numbers (in this case, numbers from 1 to 10), how many unique combinations of six numbers are there? The short answer is 210. However, I would like to know what these combinations are.

I have put the following code together. The first while loop works fine to create a lot of sorted combinations, however, I haven’t been able to print out only the unique line combinations. How can I print out these unique lines?

my %hash;
my @sorted_numbers;

# make all permutations with numbers from 1 to 10
my $permutor = List::Permutor->new (1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
while ( my @permutation = $permutor->next() ) {
        my $string = "@permutation";
        my ($N1, $N2, $N3, $N4, $N5, $N6, $N7, $N8, $N9, $N10) = split (/ /, $string);

        # chose only the first six numbers and sort them in ascending order
        my @numbers = ($N1, $N2, $N3, $N4, $N5, $N6);
        @sorted_numbers = sort {$a <=> $b} @numbers;
}

# print out the unique number combinations from the temp file
my @unique_combinations = uniq @sorted_numbers;
foreach ( @unique_combinations ) {
    print $_, "\n";
}

Answer 1

There are probably other CPAN modules for this, but here’s one way:

use Math::Combinatorics qw(combine);
my @comb = combine(6, 1..10);