fixed - using walk - missed out an obvious ommission

2 files changed, 33 insertions, 13 deletions

diff --git a/challenge-125/james-smith/perl/BinaryTree.pm b/challenge-125/james-smith/perl/BinaryTree.pm
index 1cbcbfc511..05703c9b26 100644
--- a/challenge-125/james-smith/perl/BinaryTree.pm
+++ b/challenge-125/james-smith/perl/BinaryTree.pm
@@ -32,18 +32,13 @@ sub depth {
 
 sub diameter {
   my $self = shift;
-  return 1 + $self->left->depth + $self->right->depth if $self->has_left && $self->has_right;
-
-  my $diameter = $self->depth; ## Case 1 has a single depth....
-  my $t = $self->has_left ? $self->left : $self->right;
-  while( $t->has_left || $t->has_right ) {
-    if( $t->has_left && $t->has_right ) {
-      my $d = 1 + $t->left->depth + $t->right->depth;
-      return $d > $diameter ? $d : $diameter;
-    }
-    $t = $t->has_left ? $t->left : $t->right;
-  }
-  return $diameter;
+  my $global = { 'diameter' => 0 };
+  $self->walk( sub {
+    my $d = ($_[0]->has_left  ? $_[0]->left->depth  : 0 ) +
+            ($_[0]->has_right ? $_[0]->right->depth : 0 );
+    $_[1]{'diameter'} = $d if $d > $_[1]->{'diameter'};
+  }, $global );
+  return $global->{'diameter'};
 }
 
 sub value {
diff --git a/challenge-125/james-smith/perl/ch-2.pl b/challenge-125/james-smith/perl/ch-2.pl
index d4d2cb738d..71d510b253 100644
--- a/challenge-125/james-smith/perl/ch-2.pl
+++ b/challenge-125/james-smith/perl/ch-2.pl
@@ -72,6 +72,31 @@ $x->dump;
 say sprintf 'Max depth: %d, diameter %d', $x->depth, $x->diameter;
 say '';
 
+## 1 -> 2 -> 3 -> 4 -> 5 -> 6
+##        `>10 `> 7 -> 8 -> 9
+## --------------------------
+## 9 -> 8 -> 7 -> 3 -> 4 -> 5 -> 6
+
+$x = BinaryTree->new(1)->add_child_left(
+          BinaryTree->new(2)->add_child_left(
+            BinaryTree->new(3)->add_child_left(
+              BinaryTree->new(4)->add_child_left(
+                BinaryTree->new(5)->add_child_left( BinaryTree->new(6) )
+              )
+            )->add_child_right(
+              BinaryTree->new(7)->add_child_left(
+                BinaryTree->new(8)->add_child_left( BinaryTree->new(9) )
+              )
+            )
+          )->add_child_right( BinaryTree->new(10))
+       );
+
+say '4) Tree with node further down having two children - but distance from';
+say '   root to node is greater than the depth of either child';
+$x->dump;
+say sprintf 'Max depth: %d, diameter %d', $x->depth, $x->diameter;
+say '';
+
 ## This time both child trees have depths longer than the number of
 ## ancestor nodes - so that is used to get the length...
 
@@ -80,7 +105,7 @@ say '';
 ## ---------------------
 ## 6 -> 5 -> 2 -> 3 -> 4 [ diameter 5 ]
 
-say '4) Tree with node further down having two children - but distance from';
+say '5) Tree with node further down having two children - but distance from';
 say '   root to node is less than the depth of both children';
 $x = BinaryTree->new(1)->add_child_left(
        BinaryTree->new(2)->add_child_left(