From fd8e32585a0b9d3abcc7c22c3f30e19354a039ef Mon Sep 17 00:00:00 2001
From: drbaggy <js5@sanger.ac.uk>
Date: Mon, 7 Dec 2020 08:44:10 +0000
Subject: new ch1/2

---
 challenge-090/james-smith/perl/ch-1.pl | 28 ++++++++++++++++++++++++++++
 challenge-090/james-smith/perl/ch-2.pl | 30 ++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 challenge-090/james-smith/perl/ch-1.pl
 create mode 100644 challenge-090/james-smith/perl/ch-2.pl

diff --git a/challenge-090/james-smith/perl/ch-1.pl b/challenge-090/james-smith/perl/ch-1.pl
new file mode 100644
index 0000000000..0970dfd554
--- /dev/null
+++ b/challenge-090/james-smith/perl/ch-1.pl
@@ -0,0 +1,28 @@
+#!/usr/local/bin/perl
+
+use strict;
+
+use warnings;
+use feature qw(say);
+use Test::More;
+
+## Ah! The day job....
+## Both these we've always used `tr` for as the fastest way to compute the
+## DNA count and to get reverse complement of sequence
+
+my $seq = 'GTAAACCCCTTTTCATTTAGACAGATCGACTCCTTATCCATTCTCAGAGATGTGTTGCTGGTCGCCG';
+
+is( revcomp($seq), 'CGGCGACCAGCAACACATCTCTGAGAATGGATAAGGAGTCGATCTGTCTAAATGAAAAGGGGTTTAC' );
+is_deeply( counts($seq), { 'T' => 22, 'A' => 14, 'C' => 18, 'G' => 13 } );
+
+done_testing();
+
+sub counts {
+  return { 'T' => $_[0] =~ tr/T/T/, 'A' => $_[0] =~ tr/A/A/,
+           'C' => $_[0] =~ tr/C/C/, 'G' => $_[0] =~ tr/G/G/, };
+}
+
+sub revcomp {
+  return reverse $_[0] =~ tr/ATCG/TAGC/r;
+}
+
diff --git a/challenge-090/james-smith/perl/ch-2.pl b/challenge-090/james-smith/perl/ch-2.pl
new file mode 100644
index 0000000000..618a88f999
--- /dev/null
+++ b/challenge-090/james-smith/perl/ch-2.pl
@@ -0,0 +1,30 @@
+#!/usr/local/bin/perl
+
+use strict;
+
+use warnings;
+use feature qw(say);
+use Test::More;
+
+## This is ripe for bit operators - as it is about multiplying/diving by 2...
+## and checking for the value of the "1s" bit....
+
+foreach(1..10) {
+  my $x = int rand(40);
+  my $y = int rand(40);
+  is( eth_mult( $x , $y ), $x*$y );
+}
+
+done_testing();
+
+sub eth_mult {
+  my( $n, $m ) = @_;
+  my $res = 0;
+  while($n) {
+    $res += $m if $n&1;
+    $m<<=1;
+    $n>>=1;
+  }
+  return $res;
+}
+
-- 
cgit 


From 3ba9a510b320260dda112c82a404c6b33c2958cd Mon Sep 17 00:00:00 2001
From: drbaggy <js5@sanger.ac.uk>
Date: Mon, 7 Dec 2020 15:44:39 +0000
Subject: added verbose mode to show workings

---
 challenge-090/james-smith/perl/ch-2.pl | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/challenge-090/james-smith/perl/ch-2.pl b/challenge-090/james-smith/perl/ch-2.pl
index 618a88f999..a8227b59f2 100644
--- a/challenge-090/james-smith/perl/ch-2.pl
+++ b/challenge-090/james-smith/perl/ch-2.pl
@@ -8,23 +8,38 @@ use Test::More;
 
 ## This is ripe for bit operators - as it is about multiplying/diving by 2...
 ## and checking for the value of the "1s" bit....
+#
+# To execute as a quiet test - use `perl ch-2.pl`
+#
+# To show workings run `perl ch-2.pl 1`
 
+my $flag = @ARGV && $ARGV[0] eq '1' ? 1 : 0;
 foreach(1..10) {
-  my $x = int rand(40);
-  my $y = int rand(40);
-  is( eth_mult( $x , $y ), $x*$y );
+  my $x = 100 + int rand(400);
+  my $y = 100 + int rand(400);
+  is( eth_mult( $x , $y, $flag ), $x*$y );
 }
 
 done_testing();
 
 sub eth_mult {
-  my( $n, $m ) = @_;
+  my( $n, $m, $verbose ) = @_;
+  $verbose ||= 0;
+  my $calc = $n*$m;
   my $res = 0;
+  say q() if $verbose;
   while($n) {
+    printf "%7d x %7d | %7s\n", $n, $m, $n&1 ? $m : q(.) if $verbose;
+    # The meat - use binary and
     $res += $m if $n&1;
     $m<<=1;
     $n>>=1;
   }
+  if( $verbose ) {
+    say    q(------------------+--------);
+    printf "                  | %7d (%7d)\n", $res, $calc;
+    say q();
+  }
   return $res;
 }
 
-- 
cgit