#!/usr/bin/perl

use strict;
use warnings;

my @sim_st = qw(
    1.0    0.9    0.3    0.6    0.3    0.3    0.2    0.3    0.3
    0.9    1.0    0.3    0.5    0.3    0.1    0.2    0.3    0.4
    0.3    0.3    1.0    0.6    0.3    0.2    0.2    0.3    0.4
    0.6    0.6    0.6    1.0    0.2    0.2    0.3    0.4    0.5
    0.3    0.3    0.3    0.2    1.0    0.1    0.3    0.4    0.5
    0.3    0.2    0.2    0.2    0.1    1.0    0.2    0.3    0.2
    0.1    0.2    0.2    0.3    0.3    0.1    1.0    0.8    0.6
    0.3    0.3    0.2    0.4    0.4    0.3    0.8    1.0    0.8
    0.3    0.4    0.4    0.5    0.5    0.2    0.6    0.8    1.0
);

my @sim_om = @sim_st;

use Benchmark 'cmpthese';

my $count = shift || -1;
cmpthese $count, {
    sort_with_st => \&sort_st,
    sort_with_om => \&sort_om,
};

sub sort_st {
    my @sim = @sim_st;
    my @sorted =
       map { $_->[0] }
          map {
            my $i = 0;
            sort { $b->[1] <=> $a->[1] }
                 map { [$i++, $_] } splice (@sim, 0, 9)
         }
         0..8;
}

use constant { M => 9, N => 9 };
sub sort_om {
   my @index_sorted;
   for my $m (0..(M-1)) {
      my $ix0 = $m * N;
      push @index_sorted,
           sort { $sim_om[$ix0 + $b] <=> $sim_om[$ix0 + $a] }
                0..(N-1);
   }
}