I suspect this isn't bulletproof, but it appears to work for the given example:
update2: after some thinking, I'm convinced it's ok.
#!perl -w
use strict;
my $end = shift || 40;
my $i = merge_multiple(@ARGV ? @ARGV : (2,3,5));
print $i->(),"\n" for 1 .. $end;
sub merge_multiple {
my $last = 0;
my %vals = map { $_ => $_ } sort { $a <=> $b } @_;
my %vals = map { $_ => $_ } @_;
sub {
for (keys %vals) {
$vals{$_} += $_ if $vals{$_} <= $last;
}
my ($r) = sort { $a <=> $b } values %vals;
$last = $r;
}
}
Cheers.
update: removed legacy sort, wasn't used anyway.