#!/usr/bin/env perl

use strict;
use warnings;

use Benchmark qw{cmpthese};

cmpthese -1 => {
    splice_unique => \&splice_unique,
    shift_unique  => \&shift_unique,
    map_unique    => \&map_unique,
};

sub splice_unique {
    my @sorted = sort qw{q w e r t y q w e r t y};
    my $last = '';
    my @unique;

    while (@sorted) {
        my $element = splice @sorted, 0, 1;

        if ($last ne $element) {
            $last = $element;
            push @unique, $element
        }
    }
}

sub shift_unique {
    my @sorted = sort qw{q w e r t y q w e r t y};
    my $last = '';
    my @unique;

    while (@sorted) {
        my $element = shift @sorted;

        if ($last ne $element) {
            $last = $element;
            push @unique, $element
        }
    }
}

sub map_unique {
    my @sorted = sort qw{q w e r t y q w e r t y};
    my $last = '';
    my @unique = map { $last eq $_ ? () : ($last = $_) } @sorted;
}