#!/usr/bin/perl

use warnings;
use strict;
use Benchmark qw/:hireswallclock cmpthese/;

my @ary = (0..10);                      #only IV
my $len = $#ary;
my @ary2 = @ary;
my @ary3 =qw/0 1 2 3 4 5 6 7 8 9 10/;   #only PV
print "ARRAY: @ary2\n";                 # IV -> PVIV

cmpthese (-3, {
    'IV' => sub {
        foreach my $i (0..$len-1) {
            foreach my $j ($i+1..$len) {
                my @permuted = @ary;
                @permuted[$i, $j] = @permuted[$j, $i];
            }
        }
    },
    'PVIV' => sub {
        foreach my $i (0..$len-1) {
            foreach my $j ($i+1..$len) {
                my @permuted = @ary2;
                @permuted[$i, $j] = @permuted[$j, $i];
            }
        }
    },
    'PV' => sub {
        foreach my $i (0..$len-1) {
            foreach my $j ($i+1..$len) {
                my @permuted = @ary3;
                @permuted[$i, $j] = @permuted[$j, $i];
            }
        }
    },

});