Merge pull request #505 from rabbiveesh/master

Added answers to challenge 20. Many regexes

4 files changed, 46 insertions, 0 deletions

diff --git a/challenge-020/veesh-goldman/blog.txt b/challenge-020/veesh-goldman/blog.txt
new file mode 100644
index 0000000000..b66597e216
--- /dev/null
+++ b/challenge-020/veesh-goldman/blog.txt
@@ -0,0 +1 @@
+http://blogs.perl.org/users/veesh/2019/08/solving-two-problems.html
diff --git a/challenge-020/veesh-goldman/perl5/ch-01.sh b/challenge-020/veesh-goldman/perl5/ch-01.sh
new file mode 100755
index 0000000000..14c1ada7e3
--- /dev/null
+++ b/challenge-020/veesh-goldman/perl5/ch-01.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+perl -pE'split / /, s/(.) \g1*/$& /gx'
diff --git a/challenge-020/veesh-goldman/perl5/ch-02.pl b/challenge-020/veesh-goldman/perl5/ch-02.pl
new file mode 100755
index 0000000000..31c6dedd42
--- /dev/null
+++ b/challenge-020/veesh-goldman/perl5/ch-02.pl
@@ -0,0 +1,25 @@
+#! /usr/bin/env perl
+use v5.22;
+
+sub sum_of_proper_divisors {
+  #start with one, because that is always a divisor
+  my $sum = 1;
+  (1 x shift) =~ /^ (..+) \g1+ $ (?{ $sum += length $1 }) ./xg;
+  return $sum
+}
+
+sub has_amicable {
+  my $start = shift;
+  my $pair = sum_of_proper_divisors($start);
+  #sometimes the sum of the divisors IS the number. But that's not amicable
+  return 0 if $pair == $start;
+  return $start == sum_of_proper_divisors $pair;
+}
+
+
+my $num;
+while (1) {
+  last if has_amicable(++$num);
+}
+
+say "$num, ${\sum_of_proper_divisors($num)} is your pair"
diff --git a/challenge-020/veesh-goldman/perl5/t/factors.t b/challenge-020/veesh-goldman/perl5/t/factors.t
new file mode 100644
index 0000000000..7467115a68
--- /dev/null
+++ b/challenge-020/veesh-goldman/perl5/t/factors.t
@@ -0,0 +1,17 @@
+use Test2::V0;
+
+
+sub sum_factors {
+  my $expansion = 1 x shift;
+  my $sum = 1;
+  $expansion =~ /^(..+) \g1+ $ (?{ $sum += length $1 }) ./xg;
+
+  return $sum
+}
+
+is sum_factors(4), 3;
+is sum_factors(220), 284;
+is sum_factors(284), 220;
+
+
+done_testing;