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#!/usr/bin/perl
#
# Perl Weekly Challenge - 067
#
# Task #1: Number Combinations
#
# https://perlweeklychallenge.org/blog/perl-weekly-challenge-067/
#
use strict;
use warnings;
use Test::More;
use List::Util qw(uniq);
is( comb(5, 2),
'[ [1, 2], [1, 3], [1, 4], [1, 5], [2, 3], [2, 4], [2, 5], [3, 4], [3, 5], [4, 5] ]',
'testing m=5; n=2' );
is( comb(5, 3),
'[ [1, 2, 3], [1, 2, 4], [1, 2, 5], [1, 3, 4], [1, 3, 5], [1, 4, 5], [2, 3, 4], [2, 3, 5], [2, 4, 5], [3, 4, 5] ]',
'testing m=5; n=3' );
is( comb(5, 4),
'[ [1, 2, 3, 4], [1, 2, 3, 5], [1, 2, 4, 5], [1, 3, 4, 5], [2, 3, 4, 5] ]',
'testing m=5; n=4' );
is( comb(5, 5),
'[ [1, 2, 3, 4, 5] ]',
'testing m=5; n=5' );
done_testing;
sub comb {
my ($m, $n) = @_;
die "ERROR: Missing 'm'.\n"
unless defined $m;
die "ERROR: Missing 'n'.\n"
unless defined $n;
die "ERROR: Invalid m=$m (m>0).\n"
unless ($m > 0);
die "ERROR: Invalid n=$n (n>0).\n"
unless ($n > 0);
die "ERROR: Invalid n=$n (n<=m).\n"
unless ($n <= $m);
# prepare data set
my @data = ();
push @data, [1..$m] foreach (1..$n);
# generate all possible combinations
my @combinations = ('');
foreach my $members (@data) {
@combinations = map {
my $member = $_;
map $member.$_, @$members
} @combinations;
}
# filter combinations
my %filter;
foreach my $member (@combinations) {
my @uniq = uniq split //, $member;
next unless (@uniq == $n);
$filter{ sprintf("[%s]", join ', ', sort @uniq) } = 1;
}
# return sorted result
return sprintf("[ %s ]", join ', ', (sort keys %filter));
}
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