Without knowing the exact question posed, you did not need to push stuff onto @array3. All you had to do was this for that: my @array3 = sort(@array1);

As for generating the sub-arrays, give me a few minutes and I'll have something different than using indexes.

Update: working code.

#!/usr/bin/perl

use warnings;
use strict;

use Data::Dumper;
$Data::Dumper::Indent = 1;

my @array1 = (1,2,3,4,5,6,7,8,3,5,6,3,8,1,7,8);
my @array3 = sort(@array1);

my @subarrays = ( [] );
my $last = 0;
for ( @array1 ) {
    push(@subarrays, []) if $_ < $last;
    push(@{$subarrays[-1]},$_);
    $last = $_;
}

print Dumper(\@array1);
print Dumper(\@subarrays);
print Dumper(\@array3);

exit;

__END__
[download]

My assumption was that I no longer had @array1 to work with and had to create the final sorted array from @newarray.

Never assume what is required. Trust me. Ask and ask again and preferably get the specs in writing. If the spec is ambiguous, then I assure you that you will have to either do it over or have people call your code naive at best. :)

You must always remember that the primary goal is to drain the swamp even when you are hip-deep in alligators.