#! /usr/local/bin/perl -w

use strict;
use Benchmark qw/cmpthese/;

my %h;

$h{ int(rand 1_000_000) } = rand 1000 for 1..10_000;

sub min_by_sort { ( sort {$a <=> $b} keys %h )[0] }
sub min_by_scan {
    my $min = undef;
    (not defined $min or $min > $_) and $min = $_ for keys %h;
    $min;
}

print "min_by_sort = ", min_by_sort(), "\n";
print "min_by_scan = ", min_by_scan(), "\n";

cmpthese(
    shift || -5,
    {
        min_by_sort => \&min_by_sort,
        min_by_scan => \&min_by_scan,
    }
)


##</code><code>##

min_by_sort = 107
min_by_scan = 107
Benchmark: running min_by_scan, min_by_sort, each for at least 5 CPU seconds...
min_by_scan:  4 wallclock secs ( 5.44 usr +  0.00 sys =  5.44 CPU) @ 95284.97/s (n=518112)
min_by_sort:  6 wallclock secs ( 5.12 usr +  0.00 sys =  5.12 CPU) @ 152355.18/s (n=779630)
                Rate min_by_scan min_by_sort
min_by_scan  95285/s          --        -37%
min_by_sort 152355/s         60%          --

##</code><code>##

min_by_scan:  6 wallclock secs ( 5.30 usr +  0.00 sys =  5.30 CPU) @ 93681.46/s (n=496219)
min_by_sort:  6 wallclock secs ( 5.28 usr +  0.00 sys =  5.28 CPU) @ 71843.03/s (n=379421)
               Rate min_by_sort min_by_scan
min_by_sort 71843/s          --        -23%
min_by_scan 93681/s         30%          --

##</code><code>##

min_by_sort = 301
min_by_scan = 301
Benchmark: running min_by_scan, min_by_sort, each for at least 5 CPU seconds...
min_by_scan:  6 wallclock secs ( 5.48 usr +  0.01 sys =  5.48 CPU) @ 94.63/s (n=519)
min_by_sort:  6 wallclock secs ( 5.30 usr +  0.00 sys =  5.30 CPU) @ 73.14/s (n=388)
              Rate min_by_sort min_by_scan
min_by_sort 73.1/s          --        -23%
min_by_scan 94.6/s         29%          --