Add task #1 answer for challenge 018

1 files changed, 39 insertions, 0 deletions

diff --git a/challenge-018/kian-meng-ang/perl5/ch-1.pl b/challenge-018/kian-meng-ang/perl5/ch-1.pl
new file mode 100644
index 0000000000..01538d8109
--- /dev/null
+++ b/challenge-018/kian-meng-ang/perl5/ch-1.pl
@@ -0,0 +1,39 @@
+#!/usr/bin/env perl
+# vi:et:sw=4 ts=4 ft=perl
+
+use strict;
+use warnings;
+use utf8;
+use feature qw(say);
+
+# Naive and primitive approach.
+
+die 'Required at least two strings!' if @ARGV < 2;
+
+my %cnt = ();
+foreach my $str (@ARGV) {
+    my $len = length $str;
+    foreach my $l (1 .. $len) {
+        foreach my $o (0 .. $len - $l) {
+            $cnt{substr $str, $o, $l}++;
+        }
+    }
+}
+
+# See https://stackoverflow.com/a/4184957
+# See https://en.wikipedia.org/wiki/Schwartzian_transform
+my $longest = (
+    map { $_->[0] }
+    sort { $b->[1] <=> $a->[1] }
+    map { [ $_, length $_] }
+    grep { $cnt{$_} == scalar @ARGV } keys %cnt
+)[0];
+
+say $longest;
+
+1;
+
+__END__
+
+$ perl ch-1.pl ABABC BABCA ABCBA
+ABC