Merge pull request #4624 from wlmb/master

Simplify programs

2 files changed, 13 insertions, 10 deletions

diff --git a/challenge-123/wlmb/perl/ch-1.pl b/challenge-123/wlmb/perl/ch-1.pl
index da3f90362c..62b334865f 100755
--- a/challenge-123/wlmb/perl/ch-1.pl
+++ b/challenge-123/wlmb/perl/ch-1.pl
@@ -16,14 +16,17 @@ foreach(@ARGV){
 }
 
 sub ugly {
-    my $n=shift @_; # desired ugly number
-    while($n>@uglies){
-	my ($next_id)=sort {$uglies[$u_id[$a]]*$factors[$a]<=>$uglies[$u_id[$b]]*$factors[$b]}
-	               (0..2);
-	my $next_val=$uglies[$u_id[$next_id]]*$factors[$next_id];
+    my $n=shift @_; # desired ugly number. Assume a positive integer
+    while($n>@uglies){ # generate uglies until the n-th becomes known
+	my ($next_id)=sort {next_from_id($a)<=>next_from_id($b)} 0..2;
+	my $next_val=next_from_id($next_id);
 	$u_id[$next_id]++;
-	next unless $next_val>$uglies[-1];
-	push @uglies, $next_val;
+	push @uglies, $next_val if $next_val>$uglies[-1];
     }
     return $uglies[$n-1];
 }
+
+sub next_from_id {
+    my $id=shift @_;
+    return $uglies[$u_id[$id]]*$factors[$id];
+}
diff --git a/challenge-123/wlmb/perl/ch-2.pl b/challenge-123/wlmb/perl/ch-2.pl
index 01fca9c85a..4130be36f3 100755
--- a/challenge-123/wlmb/perl/ch-2.pl
+++ b/challenge-123/wlmb/perl/ch-2.pl
@@ -9,18 +9,18 @@ use v5.12;
 use PDL;
 foreach(@ARGV){
     # assume data as strings "[[x0,y0],[x1,y1],[x2,y2],[x3,y3]]"
-    my $m=pdl($_);
+    my $m=pdl($_); # convert to 2d array
     # Separate into four vectors, translate the origin to the first
     # and sort by size
     my $v0=$m->slice(":,(0)");
     my (undef, $s1, $s2, $d)=sort {size2($a) <=> size2($b)} map {$_-$v0} $m->dog;
     # $s1 and $s2 ought to be the sides and $d the diagonal
-    # check they add up and their sizes.
+    # check they add up and their sizes. I use 'approx' to accommodate rounding errors.
     my $ok=approx(size2($s1+$s2-$d),0) && approx(size2($s1),size2($s2))
            && approx(size2($d),2*size2($s1));
     say "Input: $m Output: $ok"
 }
-sub size2 { #size of vector squared
+sub size2 { #  squared size of vector
     my $v=shift @_;
     return ($v*$v)->sumover;
 }