Create ch-1.pl

1 files changed, 38 insertions, 0 deletions

diff --git a/challenge-212/james-smith/perl/ch-1.pl b/challenge-212/james-smith/perl/ch-1.pl
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+#!/usr/local/bin/perl
+
+use strict;
+use warnings;
+use feature qw(say);
+use Test::More;
+
+my @TESTS = (
+  [ ['Perl',2,22,19,9], 'Raku' ],
+  [ ['Raku',24,4,7,17], 'Perl' ],
+);
+
+
+sub jumping_letters {
+                         # Stitch back into word
+  return join '',
+                         # Like ord below chr acts on $_ if no parameters
+                         # are passed...
+         map { chr }
+                         # Do the maths.... now this is where things get
+                         # a little cheeky.... ord acts on $_ which is the
+                         # letter, shift returns the next value of @_ which
+                         # is the shift!
+                         # 96&ord| .... preserves the 64 & 32 bit - it is
+                         # the 32 represents upper or lowercase
+                         # the 64 indicates that this is a letter (sort of)
+                         # 31&ord removes these and returns the numeric
+                         # position of the number in the alphabet - we subtract
+                         # one to get the zero based position + shift it
+                         # wrap and them move back to a one based position.
+         map { (96&ord) | ( (31&ord) -1 + shift)%26 +1 }
+                         # Split into individual letters;
+         split //,
+                         ## This is the word we are "changing"
+         shift;
+}
+
+is( jumping_letters( @{$_->[0]} ), $_->[1] ) for @TESTS;