#!/usr/bin/perl

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

my @ary = (0..5);
my $len = $#ary;
my @ary2 = @ary;
print "ARRAY: @ary2\n";  # numbers -> strings
#$_ += 0 foreach @ary2;  # stings -> numbers

#print "@ary\n";

cmpthese (-3, {
   'intervals' => sub {
        foreach my $i (0..$len-1) {
            foreach my $j ($i+1..$len) {
                my @permuted = @ary[0..$i-1, $j, $i+1..$j-1, $i, $j+1..$len];
            }
        }
    },
    'cross' => sub {
        foreach my $i (0..$len-1) {
            foreach my $j ($i+1..$len) {
                my @permuted = @ary;
                @permuted[$i, $j] = @permuted[$j, $i];
            }
        }
    },
   'intervals2' => sub {
        foreach my $i (0..$len-1) {
            foreach my $j ($i+1..$len) {
                my @permuted = @ary2[0..$i-1, $j, $i+1..$j-1, $i, $j+1..$len];
            }
        }
    },
    'cross2' => sub {
        foreach my $i (0..$len-1) {
            foreach my $j ($i+1..$len) {
                my @permuted = @ary2;
                @permuted[$i, $j] = @permuted[$j, $i];
            }
        }
    },
});