Add ch-2.pl for letter phone task

1 files changed, 45 insertions, 0 deletions

diff --git a/challenge-067/simon-miner/perl/ch-2.pl b/challenge-067/simon-miner/perl/ch-2.pl
new file mode 100755
index 0000000000..b3856a6dc8
--- /dev/null
+++ b/challenge-067/simon-miner/perl/ch-2.pl
@@ -0,0 +1,45 @@
+#!/usr/local/bin/perl
+
+use strict;
+use warnings;
+
+my @letters = (
+    ['+'],    # Need some way to track 0 to avoid colliding strings.
+    [ '_', ',', '@' ],
+    [qw( A B C )],
+    [qw( D E F )],
+    [qw( G H I )],
+    [qw( J K L )],
+    [qw( M N O )],
+    [qw( P Q R S )],
+    [qw( T U V )],
+    [qw( W X Y Z )],
+);
+
+my $S = shift( @ARGV );
+die "Stringcan only contain digits 0-9" if $S =~ m/[\D]/;
+
+my @letter_strings = get_letter_strings( $S );
+print join( "\n", @letter_strings ) . "\n";
+
+sub get_letter_strings {
+    my ( $S ) = @_;
+    return () unless $S;
+
+    $S =~ s/^(\d)// && ( my $digit = $1 );
+
+    my @letter_strings = ();
+    my @letters        = @{ $letters[$digit] };
+    if ( $S ) {
+        for my $letter ( @letters ) {
+            for my $letter_string ( get_letter_strings( $S ) ) {
+                push( @letter_strings, $letter . $letter_string );
+            }
+        }
+    }
+    else {
+        @letter_strings = @letters;
+    }
+
+    return @letter_strings;
+}