From 05e96cba9ec7a4b3369202dd79b7873fba04f416 Mon Sep 17 00:00:00 2001
From: Steven Wilson <steven1170@zoho.eu>
Date: Tue, 2 Jul 2019 20:06:49 +0100
Subject: improve encode/decode subroutines

---
 challenge-015/steven-wilson/perl5/ch-2.pl | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/challenge-015/steven-wilson/perl5/ch-2.pl b/challenge-015/steven-wilson/perl5/ch-2.pl
index e9c262d986..543be7ee3b 100644
--- a/challenge-015/steven-wilson/perl5/ch-2.pl
+++ b/challenge-015/steven-wilson/perl5/ch-2.pl
@@ -16,8 +16,7 @@ use warnings;
 use feature qw / say /;
 use Test::More;
 
-my @alphabet = ("A".."Z");
-my ($operation, $keyword, $in_text) = ($ARGV[0], $ARGV[1], $ARGV[2]);
+my ( $operation, $keyword, $in_text ) = ( $ARGV[0], $ARGV[1], $ARGV[2] );
 my $out_text;
 my %operations = (
     '-e' => 'encrypted',
@@ -28,11 +27,11 @@ ok( encode( "ATTACKATDAWN", "LEMON" ) eq "LXFOPVEFRNHR", "encode working" );
 ok( decode( "LXFOPVEFRNHR", "LEMON" ) eq "ATTACKATDAWN", "decode working" );
 done_testing();
 
-if ($operation eq "-e"){
-    $out_text = encode($in_text, $keyword);
+if ( $operation eq "-e" ) {
+    $out_text = encode( $in_text, $keyword );
 }
-elsif ($operation eq "-d"){
-    $out_text = decode($in_text, $keyword);
+elsif ( $operation eq "-d" ) {
+    $out_text = decode( $in_text, $keyword );
 }
 else {
     die "$operation is not a valid operation";
@@ -43,10 +42,10 @@ say "Message $operations{$operation} to '$out_text'";
 sub encode {
     my ( $plaintext, $keyword ) = @_;
     my $cyphertext;
-    for my $i (0..((length $plaintext) - 1)){
-        (my $mi) = grep { $alphabet[$_] eq substr($plaintext, $i, 1) } (0..@alphabet-1);
-        (my $ki) = grep { $alphabet[$_] eq substr($keyword, ($i % length $keyword), 1)} (0..@alphabet-1);
-        $cyphertext .= $alphabet[($mi + $ki) % 26];
+    for my $i ( 0 .. ( ( length $plaintext ) - 1 ) ) {
+        my $mi = ord( substr( $plaintext, $i, 1 ) ) - 65;
+        my $ki = ord( substr( $keyword, ( $i % length $keyword ), 1 ) ) - 65;
+        $cyphertext .= chr( ( ( $mi + $ki ) % 26 ) + 65 );
     }
     return $cyphertext;
 }
@@ -54,10 +53,10 @@ sub encode {
 sub decode {
     my ( $cyphertext, $keyword ) = @_;
     my $plaintext;
-    for my $i (0..((length $cyphertext) - 1)){
-        (my $ci) = grep { $alphabet[$_] eq substr($cyphertext, $i, 1) } (0..@alphabet-1);
-        (my $ki) = grep { $alphabet[$_] eq substr($keyword, ($i % length $keyword), 1)} (0..@alphabet-1);
-        $plaintext .= $alphabet[($ci - $ki) % 26];
+    for my $i ( 0 .. ( ( length $cyphertext ) - 1 ) ) {
+        my $ci = ord( substr( $cyphertext, $i, 1 ) ) - 65;
+        my $ki = ord( substr( $keyword, ( $i % length $keyword ), 1 ) ) - 65;
+        $plaintext .= chr( ( ( $ci - $ki ) % 26 ) + 65 );
     }
     return $plaintext;
 }
-- 
cgit