Merge branch 'bpetering'

leto · Aug 1, 2009 · 53a8517 · 53a8517
2 parents 3d5e772 + 334d879
commit 53a8517
Showing 1 changed file with 63 additions and 0 deletions.
diff --git a/perl6/003/01.pl b/perl6/003/01.pl
@@ -0,0 +1,63 @@
+use v6;
+
+=begin pod
+
+The prime factors of 13195 are 5, 7, 13 and 29.
+
+What is the largest prime factor of the number 600851475143 ?
+
+=end pod
+
+class PrimeIter {
+    has $!cur = 2;
+    method next {
+        ($!cur++ and return 1) if $!cur == 1;
+        ($!cur++ and return 2) if $!cur == 2;
+        ($!cur++ and return 3) if $!cur == 3;
+        $!cur++;
+        $!cur++ while ! self.cur_is_prime;
+        return $!cur;
+    }
+    method reset {
+        $!cur = 2;
+    }
+    method cur_is_prime {
+        # uncomment & rename method for easy conversion to normal sub :)
+        #my $n = @_.shift;
+        my $n = $!cur;
+
+        return 0 if $n % 2 == 0;
+        return 1 if $n < 4;
+
+        my $x = 3;
+        while ( $x <= sqrt $n ) {
+            return 0 unless $n % $x;
+            $x += 2;
+        }
+        return 1;
+    }    
+}
+
+my $to_factor = 600851475143;
+my $pi = PrimeIter.new;
+
+my @prime_factors;
+my $n = $to_factor;
+
+while $n > 1 {
+    my $try_prime = $pi.next;
+    #say "tp = $try_prime";
+    if $n % $try_prime == 0 {
+        @prime_factors.unshift($try_prime);
+        $n /= $try_prime;
+        #say "removed $try_prime, n=$n";
+        $pi.reset;
+    }
+}
+
+say @prime_factors[0];
+
+#say "{@prime_factors}";     # array interp broken in rakudo 2009-07-25
+
+
+