Merge pull request #5633 from wlmb/challenges

Simplify and optimize

1 files changed, 15 insertions, 9 deletions

diff --git a/challenge-151/wlmb/perl/ch-2.pl b/challenge-151/wlmb/perl/ch-2.pl
index 28fe08d2e2..34b6778e17 100755
--- a/challenge-151/wlmb/perl/ch-2.pl
+++ b/challenge-151/wlmb/perl/ch-2.pl
@@ -5,19 +5,25 @@
 # See https://wlmb.github.io/2022/02/07/PWC151/#task-2-rob-the-house
 use v5.12;
 use warnings;
+use Memoize;
+memoize("optimize");
 die "Usage: ./ch-1.pl V0 [V1]...\n"
     . "to optimize the robery of houses 0, 1,... with valuables V0, V1..."
     unless @ARGV;
-my ($value,@houses)=optimize(0,@ARGV);
-say "Output: $value Houses: ", join ", ", @houses;
+my @values=@ARGV;
+my ($value,@houses)=optimize(0);
+say "Input: ", join ", ", @values;
+say "Output: $value";
+say "Houses: ", join ", ", @houses;
 sub optimize {
-    my ($this, $value, @rest)=@_;
-    return (0) unless defined $value; # No more houses
-    return ($value, $this) unless @rest; # Only one house left
-    my ($v1, @h1)=optimize($this+1, @rest); # what if I skip this house?
-    my ($v2, @h2)=optimize($this+2, @rest[1..@rest-1]); # what if I rob this and skip next?
+    my $first=shift;
+    my $value=$values[$first];
+    return (0) if $first >= @values; # No more houses
+    return ($value, $first) if $first==@values-1; # Only one house left
+    my ($v1, @h1)=optimize($first+1); # what if I skip first house?
+    my ($v2, @h2)=optimize($first+2,); # what if I rob first and skip next?
     my $v3=$value+$v2;
     $v3>$v1 # which option is best?
-	?($v3, $this, @h2) # This one and skip next
-	:($v1, @h1); # or skip this one
+	?($v3, $first, @h2) # First one and skip next
+	:($v1, @h1); # or skip first one
 }