use strict;
use warnings;
use List::Util 'reduce';
use Benchmark qw(cmpthese);

our $path = shift || '/usr/bin/*';
 
sub badsort {
    my @list = sort {
        (stat $b)[9] <=> (stat $a)[9] 
    } glob "$path";

    my $newest = $list[0];
}

sub goodsort {
    my %file_date;
    for ( glob "$path" ) {
         $file_date{$_} = (stat)[9];
    }
    my $newest = ( sort { $file_date{$b} <=> $file_date{$a} } keys %file_date )[0];
}

sub badreduce {
    my $newest = reduce {
        (stat $a)[9] < (stat $b)[9] ? $b : $a
    } glob "$path";
}

sub goodreduce {
    my $newest = (
        reduce { $a->[1] < $b->[1] ? $b : $a }
        map { [ $_, (stat)[9] ] }
        glob "$path"
    )->[0];
}

sub d {
    my %file_date;
    my $max = -99999999; # set it to first file's mtime would be better 
                                # but just for demonstration here
    my $mtime;
    my $file;
    for ( glob "$path" ) {
        $mtime = (stat)[9];
        if ($max <= $mtime) {
            $file =  $_;
            $max = $mtime;
        }
    }
      
    my $newest = $file;
}

sub e {
    my @array = `ls -lrt $path`;
    my $newest = $array[-1];
}
    
cmpthese(250, {
    zaxo_first => \&goodreduce,
    graff_hash => \&goodsort,
    more_stats => \&badreduce,
    most_stats => \&badsort,
    sk_maxfile => \&d,
    the_ls_lrt => \&e,
});