Some notes on the display function

1 files changed, 11 insertions, 6 deletions

diff --git a/challenge-100/james-smith/perl/ch-2.pl b/challenge-100/james-smith/perl/ch-2.pl
index f46b12cf6f..a2f18d481e 100644
--- a/challenge-100/james-smith/perl/ch-2.pl
+++ b/challenge-100/james-smith/perl/ch-2.pl
@@ -60,23 +60,28 @@ sub triangle_sum_1point5_liner {
   $b->[0];
 }
 
+## A subroutine to display the triangle indicating the route!
 sub display_sum {
-  my @tri = @_;
-  my @route;
+  my @tri = map{ [@{$_}] } @_; ## Deep copy the triangle as the search is destructive
+  my @route; ## For each node in the "current" bottom row, the route is the list
+             ## of indecies of the child nodes that make up the "optimal" path
+             ## use implicit my on $b....
   while(@{$b = pop @tri}>1) {
     ($tri[-1][$_],$route[$_]) = $b->[$_]<$b->[$_+1]
       ? ( $tri[-1][$_] + $b->[$_],   [$_,  @{$route[$_  ]||[]}] )
       : ( $tri[-1][$_] + $b->[$_+1], [$_+1,@{$route[$_+1]||[]}] ) foreach 0..@tri-1;
   }
-  @route = (0,@{$route[0]});
-  print
+  @route = (0,@{$route[0]}); ## We need to add the top node index (always 0)
+                             ## At the same time we can just take the first (only)
+                             ## path out of the 2d route matrix;
+  print ## Assume all cell numbers are single digits...
     '',
     ( map {
-      '  ' x (@_-($a=$_)),
+      '  ' x (@_-($a=$_)), ## use implicit my on $a;
       ( map {
         sprintf $route[$a]==$_ ? '[%d] ': ' %d  ' , $_[$a][$_]
       } 0..$a ),
       "\n"
     } 0..@_-1 ),
-    "\n";
+    "\nMinimum path: ",$b->[0],"\n\n";
 }