From 0911e211582f663efb0806b2c39a7d447765071a Mon Sep 17 00:00:00 2001
From: drbaggy <js5@sanger.ac.uk>
Date: Tue, 29 Sep 2020 08:50:55 +0100
Subject: rewrite with a left to right and a right to left pass - this doesn't
 need the outer loop

---
 challenge-080/james-smith/perl/ch-2.pl | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/challenge-080/james-smith/perl/ch-2.pl b/challenge-080/james-smith/perl/ch-2.pl
index a8eacfb22e..c263204651 100644
--- a/challenge-080/james-smith/perl/ch-2.pl
+++ b/challenge-080/james-smith/perl/ch-2.pl
@@ -10,6 +10,7 @@ use Test::More;
 is( candies( qw(1 2 2) ),          4 );
 is( candies( qw(1 4 3 2) ),        7 );
 is( candies( qw(5 4 3 2 1) ),     15 );
+is( candies( qw(5 4 3 4 3 2 1) ), 16 );
 is( candies( qw(2 1 2 1 2 1 2) ), 11 );
 
 done_testing;
@@ -18,18 +19,16 @@ sub candies {
   my @ranks = @_;
   my $prev_count = my @candies = map { 1 } @ranks; ## First pass we set everything to 1!
   my $flag;
-  do {
-    my $count = 0;
-    foreach( 0..(@ranks-2) ) {         ## Loop through comparing element to next one - increase as approprite
-      $candies[$_+1] = $candies[$_  ]+1 if $ranks[$_] < $ranks[$_+1] && $candies[$_] >= $candies[$_+1];
-      $candies[$_]   = $candies[$_+1]+1 if $ranks[$_] > $ranks[$_+1] && $candies[$_] <= $candies[$_+1];
-      $count        += $candies[$_  ]; ## by the time we get here we would have done both comparisons that
-                                       ## cause this entry to be updated..
-    }
-
-    $count += $candies[-1];            ## Add count for the last element...
-
-    return $count if $count == $prev_count; ## Totals are the same so nothing been update can return
-    $prev_count = $count;
-  } while( 1 ); ## Infinite loop - will hit exit condition in loop...!
+  ## Sweep left first...
+  foreach( 0..(@ranks-2) ) {
+    $candies[$_+1] = $candies[$_]+1 if $ranks[$_] < $ranks[$_+1] && $candies[$_] >= $candies[$_+1];
+  }
+  ## Then sweep right... we have to go right to left otherwise you don't get the right answer
+  ## at the end...
+  foreach( reverse 1..(@ranks-1) ) {
+    $candies[$_-1] = $candies[$_]+1 if $ranks[$_] < $ranks[$_-1] && $candies[$_] >= $candies[$_-1];
+  }
+  my $t = 0;
+  $t+= $_ foreach @candies;
+  return $t;
 }
-- 
cgit