From f2f8c5a62728a03a1346f02707e4ccb228f797e5 Mon Sep 17 00:00:00 2001
From: Roger Bell_West <roger@firedrake.org>
Date: Tue, 6 Aug 2019 16:46:15 +0100
Subject: Better divisors calculation, rather faster

---
 challenge-020/roger-bell-west/perl6/ch-2.p6 | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/challenge-020/roger-bell-west/perl6/ch-2.p6 b/challenge-020/roger-bell-west/perl6/ch-2.p6
index 9f095df46b..519f2c8866 100755
--- a/challenge-020/roger-bell-west/perl6/ch-2.p6
+++ b/challenge-020/roger-bell-west/perl6/ch-2.p6
@@ -4,17 +4,11 @@ my $a=1;
 while (1) {
   $a++;
   my @a=divisors_unself($a);
-  unless (@a) {
-    next;
-  }
   my $b=@a.sum;
   if ($b <= $a) {
     next;
   }
   my @b=divisors_unself($b);
-  unless (@b) {
-    next;
-  }
   my $aa=@b.sum;
   if ($aa == $a) {
     print "$a, $b\n";
@@ -23,10 +17,14 @@ while (1) {
 
 sub divisors_unself ($k) {
   my @d=(1);
-  for 2..$k/2.Int -> $d {
+  my @e;
+  for 2..$k.sqrt.Int -> $d {
     if ($k % $d == 0) {
-      push @d,$d;
+      push @d,$d,$k/$d;
+      if @d[*-1] == $d {
+        pop @d;
+      }
     }
   }
   return @d;
-}
\ No newline at end of file
+}
-- 
cgit