From 066ad6ac3eea1f0d02b5098ca921addade4b784f Mon Sep 17 00:00:00 2001
From: drbaggy <js5@sanger.ac.uk>
Date: Sat, 30 Jul 2022 01:25:34 +0100
Subject: tweaks and shortenings

---
 challenge-175/james-smith/README.md    | 6 ++++--
 challenge-175/james-smith/perl/ch-1.pl | 8 +++++---
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/challenge-175/james-smith/README.md b/challenge-175/james-smith/README.md
index 89f94bc409..56bf461373 100644
--- a/challenge-175/james-smith/README.md
+++ b/challenge-175/james-smith/README.md
@@ -31,7 +31,7 @@ sub last_day_of_months {
                         ## Compute the last Sunday in december of the previous year
   my $last = 31 - ( int($yr%100/4) - $ly + 6 - 2*$yr/100%4 + $yr%100 ) % 7;
                         ## Finally work out the last days of the following 2 months.
-  map { ( ($last += 35 - $L[$_-1]) > $L[$_] ) && ($last-=7);
+  map { $last-=7 if $L[$_] < ($last += 35 - $L[$_-1]);
         sprintf '%04d-%02d-%02d', $yr, $_, $last
       } 1..12
 }
@@ -95,7 +95,7 @@ We can rewrite this as a 1-liner using `List::Util`s product function.
 Now there is a second nasty trick here - which if you are used to javascript *self-executing closure*. The trick allows us here to
 use the result of the totient calculation and use it to calculate the `t(n) + S( t(n) )` calculation without a *temporary* variable.
 
-The code reduces to, watch out for the two difference `$_[]` and the `$_->[]`...:
+The code reduces to this, watch out for the two difference `$_[]` and the `$_->[]`...:
 
 ```perl
 sub st {
@@ -107,3 +107,5 @@ sub st {
                   );
 }
 ```
+
+The longer form is about 10-15% faster - due to the map and use of external method product...
diff --git a/challenge-175/james-smith/perl/ch-1.pl b/challenge-175/james-smith/perl/ch-1.pl
index 3355c93461..b4ec450c98 100644
--- a/challenge-175/james-smith/perl/ch-1.pl
+++ b/challenge-175/james-smith/perl/ch-1.pl
@@ -30,16 +30,18 @@ sub last_day_of_months {
                         ## Compute the last Sunday in december of the previous year
   my $last = 31 - ( int($yr%100/4) - $ly + 6 - 2*$yr/100%4 + $yr%100 ) % 7;
                         ## Finally work out the last days of the following 2 months.
-  map { ( ($last += 35 - $L[$_-1]) > $L[$_] ) && ($last-=7);
+  map { $last-=7 if $L[$_] < ($last += 35 - $L[$_-1]);
         sprintf '%04d-%02d-%02d', $yr, $_, $last
       } 1..12
 }
 
-#123456789#123456789#123456789#123456789#123456789#123456789#123456789#123456789
+#        1         2         3         4         5
+#23456789#123456789#123456789#123456789#123456789#1
 sub l {
   my$y=pop;
   $L[2]=(my$f=!($y%400)^!($y%100)^!($y%4))?29:28;
   my$l=31-(int($y%100/4)-$f+6-2*$y/100%4+$y%100)%7;
-  map{(($l+=35-$L[$_-1])>$L[$_])&&($l-=7);sprintf'%04d-%02d-%02d',$y,$_,$l}1..12
+  map{$l-=7if$L[$_]<($l+=35-$L[$_-1]);
+      sprintf'%04d-%02d-%02d',$y,$_,$l}1..12
 }
 
-- 
cgit