Merge pull request #481 from andrezgz/challenge-020

challenge-020 andrezgz solution

3 files changed, 59 insertions, 0 deletions

diff --git a/challenge-020/andrezgz/perl5/ch-1.pl b/challenge-020/andrezgz/perl5/ch-1.pl
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+++ b/challenge-020/andrezgz/perl5/ch-1.pl
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+#!/usr/bin/perl
+
+# https://perlweeklychallenge.org/blog/perl-weekly-challenge-019/
+# Task #1
+# Write a script to accept a string from command line and split it on change of character.
+# For example, if the string is "ABBCDEEF", then it should split like "A", "BB", "C", "D", "EE", "F".
+
+use strict;
+use warnings;
+
+my $s = $ARGV[0] || 'ABBCDEEF';
+while ($s =~ /(([A-Z])\2*)/g) { print "$1\n"; };
diff --git a/challenge-020/andrezgz/perl5/ch-1.sh b/challenge-020/andrezgz/perl5/ch-1.sh
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+# https://perlweeklychallenge.org/blog/perl-weekly-challenge-019/
+# Task #1
+# Write a script to accept a string from command line and split it on change of character.
+# For example, if the string is "ABBCDEEF", then it should split like "A", "BB", "C", "D", "EE", "F".
+perl -e 'while ($ARGV[0] =~ /(([A-Z])\2*)/g) { print "$1\n"; };' $1
diff --git a/challenge-020/andrezgz/perl5/ch-2.pl b/challenge-020/andrezgz/perl5/ch-2.pl
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+++ b/challenge-020/andrezgz/perl5/ch-2.pl
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+#!/usr/bin/perl
+
+# https://perlweeklychallenge.org/blog/perl-weekly-challenge-019/
+# Task #2
+# Write a script to print the smallest pair of Amicable Numbers.
+# For more information, please checkout wikipedia page.
+# https://en.wikipedia.org/wiki/Amicable_numbers
+
+use strict;
+use warnings;
+
+my $n = 0;
+until (amicable(++$n)) {};
+print "Smallest pair of Amicable Numbers: ($n,".amicable($n).")\n";
+
+{
+    my %cache;
+    sub amicable {
+        my $n = shift;
+
+        $cache{$n} = sum(factors($n)) unless exists $cache{$n};
+        my $m = $cache{$n};
+        return if $m == $n; # same number
+
+        $cache{$m} = sum(factors($m)) unless exists $cache{$m};
+        return if $cache{$m} != $n; # not amicable
+
+        return $m;
+    }
+}
+
+sub sum {
+    my $s = 0;
+    $s += $_ for @_;
+    return $s;
+}
+
+sub factors {
+    my $n = shift;
+    my $upto = $n == 1 ? 1 : $n/2;
+    return grep {$n % $_ == 0} (1 .. $upto);
+}