Re: Re: Prime Number Finder

[Anonymous Monk]

eisenstein's code is genius, to say the least. I found a different way of the sieve method, and am wondering which is more efficient. Thanks!

! usr/bin/perl -w
use strict;
sub prime{
my (@primes,%n);
my $n=shift;
foreach my $r(2..$n){
    $n{$r}=1;
}
foreach my $x(2..int(sqrt($n))){
    if($n{$x}){
        my $a=2*$x;
        while ($a <= $n){
            $n{$a}=undef;
            $a=$a+$x;
        }
    }
}
foreach my $x(2..$n){
    if($n{$x}){
        push( @primes, $x);    
    }
}
return @primes;
}
#find to 100
print join ',',prime(100);