#!/usr/bin/env perl

use warnings;
use strict;

my @data = (1,2,3);
my $trials = 1000000;

my %results;

my $shuffler = \&shuffle_listutil;
#my $shuffler = \&shuffle_naive;
#my $shuffler = \&shuffle_kfy;

for (1..$trials) {
    $results{join '', $shuffler->(@data)}++;
}

for my $result (sort keys %results) {
    printf "%10s %.02f%%\n", $result, $results{$result}/$trials*100;
}

sub shuffle_listutil {
    require List::Util;
    return List::Util::shuffle(@_);
}

sub shuffle_naive {
    my @data = @_;
    for my $i (0..$#data) {
        my $n = int(rand($#data+1));
        my $t = $data[$i]; $data[$i] = $data[$n]; $data[$n] = $t;
    }
    return @data;
}

sub shuffle_kfy {
    my @data = @_;
    for my $i (0..$#data) {
        my $n = int(rand($#data-$i+1))+$i;
        my $t = $data[$i]; $data[$i] = $data[$n]; $data[$n] = $t;
    }
    return @data;
}