- Added solutions by Mark Anderson.

2 files changed, 21 insertions, 0 deletions

diff --git a/challenge-018/mark-anderson/README b/challenge-018/mark-anderson/README
new file mode 100644
index 0000000000..544858a104
--- /dev/null
+++ b/challenge-018/mark-anderson/README
@@ -0,0 +1 @@
+Solutions by Mark Anderson.
diff --git a/challenge-018/mark-anderson/perl5/ch-1.pl b/challenge-018/mark-anderson/perl5/ch-1.pl
new file mode 100644
index 0000000000..8eac48c266
--- /dev/null
+++ b/challenge-018/mark-anderson/perl5/ch-1.pl
@@ -0,0 +1,20 @@
+#!/usr/bin/env perl
+
+use Modern::Perl '2018';
+use List::Util 'all';
+
+# Find the longest common substring.
+
+my @strings = @ARGV;
+my $pattern = pop @strings;
+my $longest;
+
+OUTER:
+for(my $w=length $pattern; $w>0; $w--) {
+    for(my $i=0; $i<=(length $pattern)-$w; $i++) {
+        $longest = substr $pattern, $i, $w;
+            last OUTER if all { /$longest/ } @strings;
+    }
+}
+
+say $longest;