#!/usr/bin/perl -slw
use strict;
use List::Util qw[ shuffle ];
use Benchmark qw/:all/;

sub naive (@) {
    my @l=@_;
    for (reverse 1..$#l) {
        my $r=int rand($_+1);
        @l[$_,$r]=@l[$r,$_];
    }
    @l;
}

sub listutil (@) {
    my @a=\(@_);
    my $n;
    my $i=@_;
    map {
        $n = rand($i--);
        (${$a[$n]}, $a[$n] = $a[$i])[0];
    } @_;
}

sub buk (@) {
    my @a = \( @_ );
    my $n;
    my $i = @_;
    map+( $n = rand($i--), ${ $a[ $n ] }, $a[ $n ] = $a[ $i ] )[ 1 ], @_;
}

sub bukNew ($) {
    my( $ref ) = @_;
    my @x = 0 .. $#$ref;
    @{ $ref }[ map splice( @x, rand @x, 1 ), @x ];
}

#my %stats;
#++$stats{ join' ', bukNew( ['A'..'D'] ) } for 1 .. 1e4;
#print "$_ => $stats{ $_ }" for sort keys %stats;

sub blokhead (@) {
    my @a = (0 .. $#_);
    my $i = @_;
    my $n;
    map+( $n=rand($i--), $_[$a[$n]], $a[$n]=$a[$i] )[ 1 ], @_;
}

sub blokhead_ref ($) {
    my( $ref ) = @_;
    my @a = (0 .. $#$ref);
    my $i = @$ref;
    my $n;
    map+( $n=rand($i--), $ref->[$a[$n]], $a[$n]=$a[$i] )[ 1 ], @a;
}

#%stats = ();
#++$stats{ join' ', blokhead_ref( ['A'..'D'] ) } for 1 .. 1e4;
#print "$_ => $stats{ $_ }" for sort keys %stats;

for my $c ( map{ 10**$_ }  1..3 ) {
    for my $l ( map{ 10**$_ }  0.1, 1, 3 ) {
        print "\n$c strings length $l";
        our @test = map $_ x $l, 1..$c;
        cmpthese -3, {
            bukNew => q[ bukNew( \@test ) ],
            blokhead => q[ blokhead_ref( \@test ) ],
            map {
                $_ => "$_ \@test"
            } qw/naive listutil blokhead buk/
        };
    }
}