#! perl -slw
use strict;
use vars qw[ $SIZE $N $CHUNK ];

$SIZE  ||= 100_000;
$N     ||= 30;
$CHUNK ||= 100;

srand( 1 );

sub getTopN {
	my( $aref, $n ) = @_;
	my @top = @{ $aref }[ 0 .. ( $n - 1) ];

	for( my $p = $CHUNK; $p < @$aref; $p += $CHUNK ) {
		my $end = $p + $CHUNK < @$aref ? $p + $CHUNK : $#{ $aref };
		@top = (
			sort{ $b <=> $a } @top, @{ $aref }[ $p .. $end ]
		)[ 0 .. ( $n - 1 ) ];
	}
	return @top;
}
print scalar localtime;

my @numbers;
$#numbers = $SIZE;
$numbers[ $_ ] = int rand $SIZE for 0 .. $SIZE;

print scalar localtime;
print "@{[ getTopN( \@numbers, $N ) ]}";
print scalar localtime;