2 files changed, 115 insertions, 1 deletions
diff --git a/challenge-162/mark-anderson/raku/ch-1.raku b/challenge-162/mark-anderson/raku/ch-1.raku
index f7c2bc9145..da67928192 100644
--- a/challenge-162/mark-anderson/raku/ch-1.raku
+++ b/challenge-162/mark-anderson/raku/ch-1.raku
@@ -8,7 +8,6 @@ is check-digit('012-3-456-78921-0'), 0;
 sub check-digit(\isbn)
 {
     10 - (sum isbn.chop.comb(/\d/) >>*>> < 1 3 >) mod 10
-
     andthen .item < 10 ?? .item !! 0
 }
 
diff --git a/challenge-162/mark-anderson/raku/ch-2.raku b/challenge-162/mark-anderson/raku/ch-2.raku
new file mode 100644
index 0000000000..b538b89fa7
--- /dev/null
+++ b/challenge-162/mark-anderson/raku/ch-2.raku
@@ -0,0 +1,115 @@
+#!/usr/bin/env raku
+
+use Test;
+
+class playfair
+{
+    has $!key;
+    has $!message;
+    has $!result;
+    has $!term;
+    has %!coords;
+    has @!table;
+    has @!digrams;
+
+    method table
+    {
+        @!table  = ($!key ~ ('a'..'z')).comb(/\S/).unique;
+        my $i    =  @!table.first('i'|'j', :k).succ;
+        my @tail =  @!table[$i..@!table.end].grep(/<-[ij]>/);
+        @!table  = (@!table[^$i].Array.append(@tail)).rotor(5);
+    }
+
+    method coordinates
+    {
+        for ^5 X ^5 -> ($r, $c)
+        {
+            %!coords{@!table[$r;$c]} = ($r, $c);
+        }
+    }
+
+    method digrams
+    {
+        loop
+        {
+            @!digrams = $!message.comb(/\S/).rotor(2, :partial);
+            my $i = @!digrams.first({.head eq .tail}, :k);
+            last unless defined $i;
+            last if @!digrams[$i].elems == 1;
+            $_ = (.head, 'x', .tail) given @!digrams[$i];
+            $!message = @!digrams.join;
+        }
+
+        $_ = (.head, 'x') if .elems == 1 given @!digrams[*-1];
+    }
+
+    method encrypt
+    {
+        $!term = 1;
+        self.process();
+    }
+
+    method decrypt
+    {
+        $!term = -1;
+        self.process();
+    }
+
+    multi method process
+    {
+        for @!digrams -> $d
+        {
+            $!result ~= self.process($d);
+        }
+        
+        return $!result;
+    }
+
+    multi method process($d)
+    {
+        my $h = %!coords{$d.head};
+        my $t = %!coords{$d.tail};
+
+        if $h.head eq $t.head
+        {
+            return @!table[$h.head;($h.tail + $!term) mod 5]
+                 ~ @!table[$t.head;($t.tail + $!term) mod 5] 
+        }
+
+        if $h.tail eq $t.tail
+        {
+            return @!table[($h.head + $!term) mod 5;$h.tail]
+                 ~ @!table[($t.head + $!term) mod 5;$t.tail]
+        }
+
+        return @!table[$h.head;$t.tail] 
+             ~ @!table[$t.head;$h.tail]
+    }
+    
+    method BUILD(:$key!, :$message!)
+    {
+        $!key     = $key;
+        $!message = $message;
+        self.table();
+        self.coordinates();
+        self.digrams();
+    }
+}
+
+is playfair.new(:key('playfair example'), :message('hide the gold in the tree stump')).encrypt(),
+'bmodzbxdnabekudmuixmmouvif';
+
+is playfair.new(:key('playfair example'), :message('bmodzbxdnabekudmuixmmouvif')).decrypt(),
+'hidethegoldinthetrexestump';
+
+is playfair.new(:key('perl and raku'), :message('siderwrdulfipaarkcrw')).decrypt(),
+'thewexeklychallengex';
+
+is playfair.new(:key('perl and raku'), :message('the weekly challenge')).encrypt(),
+'siderwrdulfipaarkcrw';
+
+is playfair.new(:key('scaredy cat'), :message('eeeeeeek a mouse')).encrypt(),
+'rzrzrzrzrzrzrlsomwcs';
+
+is playfair.new(:key('scaredy cat'), :message('rzrzrzrzrzrzrlsomwcs')).decrypt(),
+'exexexexexexekamouse';