Merge pull request #3371 from drbaggy/master

challenge 97

2 files changed, 85 insertions, 0 deletions

diff --git a/challenge-097/james-smith/perl/ch-1.pl b/challenge-097/james-smith/perl/ch-1.pl
new file mode 100644
index 0000000000..d6dfd58a56
--- /dev/null
+++ b/challenge-097/james-smith/perl/ch-1.pl
@@ -0,0 +1,17 @@
+#!/usr/local/bin/perl
+
+use strict;
+
+use warnings;
+use feature qw(say);
+use Test::More;
+
+is( caesar('ABCDEFGHIJKLMNOPQRSTUVWXYZ',3), 'XYZABCDEFGHIJKLMNOPQRSTUVW' );
+is( caesar('THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG',3), 'QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD' );
+
+done_testing();
+
+sub caesar {
+  return join q(), map { m{[A-Z]} ? chr 65+(ord($_)-65-$_[1])%26 : $_ } split m{}, $_[0];
+}
+
diff --git a/challenge-097/james-smith/perl/ch-2.pl b/challenge-097/james-smith/perl/ch-2.pl
new file mode 100644
index 0000000000..81f89d7e4f
--- /dev/null
+++ b/challenge-097/james-smith/perl/ch-2.pl
@@ -0,0 +1,68 @@
+#!/usr/local/bin/perl
+
+use strict;
+
+use warnings;
+use feature qw(say);
+use Test::More;
+
+is( min_flips('101101',3), 0 );
+is( min_flips('101100101',3), 1 );
+is( min_flips('10110111', 4), 2 );
+is( min_flips('100101100',3), 1 );
+is( min_flips('101100100100101',3), 2 );
+is( min_flips('0000000100100011010001010110011110001001101010111100110111101111',4), 32 );
+
+done_testing();
+
+sub min_flips {
+  ## Golf mode on...
+  ##
+  ## This was to use this to serve as an example of perl idioms that other programmers
+  ## may find it difficult to understand - and so I tried to put as many of them in relatively
+  ## short function....
+  ##
+  ## One statement functions are a lovely perl concept - even if they can get a bit difficult
+  ## to read....
+  ##
+
+  local $/;
+  return [
+    map {
+      local $\ = ( $_[0] ^ (substr$_[0],$_,$_[1]) x (length($_[0])/$_[1]) ) =~ tr/\x01/\x01/,
+      $/ = (!$_ || ($\ < $/)) ? $\ : $/
+    }
+    map { $_*$_[1] }
+    0 .. ( length($_[0])/$_[1] - 1 )
+  ]->[-1];
+  ## We could use variales here - but playing with localised special variables is fun!
+  ## $/ <- minimum value
+  ## $\ <- value for given chunk....
+  ##
+  ## The inner map + range combination returns a list of ids of the form 0, $n, 2*$n until the
+  ## end of the array, we use this to chunk the array up for comparison
+  ##
+  ## Inside the end map - we first string "xor" the string with the repeated chunk of the array.
+  ## so e.g. for the first example this becomes:
+  ##   '101100101' ^ '101'.'101'.'101'
+  ##   '101100101' ^ '100'.'100'.'100'
+  ##   '101100101' ^ '101'.'101'.'101'
+  ## if the symbols match you get a value \x00, when they don't match you get value \x01
+  ## so we then count the \x01's using tr... and store in $\
+  ##
+  ## Next if it is the first chunk OR the value of $\ is less than the current min ($/)
+  ## We set $/ to $\ otherwise we leave it as $/
+  ##
+  ## The resulting array consists of the value for the node and the running minimum in the examples
+  ##
+  ## for ex 1: it is [0,0,0,0]
+  ## for ex 2: it is [1,1,2,1,1,1]
+  ## for ex 3: it is [1,1,1,1]
+  ## for ex 4: it is [2,2,2,2]
+  ## for ex 5: it is [2,2,1,1,1,1]
+  ##
+  ## We need the last value of this so we wrap the list into an array ref and take the last element
+  ##
+  ## [ list... ]->[-1];
+}
+