#! perl -slw
use strict;

package primes;

open my $fh, '<:raw', 'data\primes.deltas.bin' or die $!;
read( $fh, my( $deltas ), -s( 'data\primes.deltas.bin' ) );
close $fh;

sub firstNprimes {
    my( $n ) = @_;
    my @primes = unpack 'C*', $deltas;
    $primes[ $_ ] += $primes[ $_ - 1 ] for 1 .. $#primes;
    return \@primes;
}

sub primeN { return unpack "%32C$_[0]", $deltas; }


package main;
use Benchmark::Timer;
die 'Supply N' unless @ARGV;

$ARGV[ 0 ] +=0; ## force numeric

my $T = new Benchmark::Timer;

$T->start( "Finding the $ARGV[ 0 ] prime" );
print "The $ARGV[ 0 ]th prime is: ",  primes::primeN( $ARGV[ 0 ] );
$T->stop( "Finding the $ARGV[ 0 ] prime" );

$T->start( "Retrieving the first $ARGV[ 0 ] primes" );
my $primes = primes::firstNprimes( $ARGV[0] );
$T->stop( "Retrieving the first $ARGV[ 0 ] primes" );
$T->report;

print "The first 100 primes are:";
print for @{ $primes }[ 0 .. 99 ];
print "The last  100 primes (of the first ARGV[ 0 ]) are:";
print for @{ $primes }[ -100 .. -1 ];