#!/usr/bin/perl
use strict;
use warnings;
use Algorithm::Loops 'NestedLoops';

my ($val, $sum, $count, $key);
my (%seen, %uniq);
my (@matches, @key);

my ($amount, $depth) = (28, 7);
my $RS = [10, 5, 13, 3, 15, 1, 4];

NestedLoops( [ ( $RS ) x $depth ], { OnlyWhen => \&ok }, sub{} );

print_results();

sub ok {
    $count++;
    %uniq = ();
    $sum = 0;
    for $val ( @_ ) {
        $uniq{$val}++;
        return 0 if $uniq{$val} > 1;
        $sum += $val;
        return 0 if $sum > $amount;
    }
    $key = join " " , sort {$b <=> $a} @_;
    return 0 if exists $seen{$key};
    $seen{$key} = undef;
    push @matches , $key if $sum == $amount;
}

sub print_results {
    my %convert;
    @convert{ @$RS } = 'A' .. 'H';
    print "Searched $count combinations...\n";
    for my $match ( @matches ) {
        for my $value ( split " " , $match ) {
            print "$convert{$value} ";
        }
        print "\n";
    }
}