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ProjectEulerProblem3.pl

#  Solution to projecteuler.net/problem=3
#  Question:
#  The prime factors of 13195 are 5, 7, 13 and 29.
#  What is the largest prime factor of the number 600851475143 ?
#  Answer: 6857
 
use strict;
use warnings;
 
my @factors;
 
getFactors(600851475143);
my %seen;
my @unique = grep { ! $seen{$_}++ } @factors;
foreach my $x (@unique) {
    print "$x\n"
}
sub getFactors {
    my $n = shift;
	if($n<1) {return;}
	if(isPrime($n)){
		push @factors, $n;
		return;
	}
	for (my $d = 2; $d <= ($n-1); $d++) 
	{
		if($n % $d == 0)
		{
			push @factors, $d;
			getFactors(int($n/$d));
			last;
		}
	}
}
sub isPrime {
	my $n = shift;
	my $c = 0;
	for (my $i = 1; $i < $n; $i++) {
		if(($n % $i) == 0)
		{
			$c++;
			if($c > 1)
			{
				return 0;
			}			
		}
	}
	if($c == 1)
	{
		return 1;
	}
	return 0;
}