fix RedBlackTree::LeafNode-s being marked red

joshuay03 · Aug 24, 2024 · 243a6b9 · 243a6b9
1 parent 1ec1acb
commit 243a6b9
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,6 @@
 ## [Unreleased]
 
+- Fix `RedBlackTree::LeafNode`s being marked red
 - Handle comparison with `RedBlackTree::LeafNode` in subclasses of `RedBlackTreeNode`
 - Add `RedBlackTree#include?`
 - Add `RedBlackTree#search`

diff --git a/lib/red-black-tree.rb b/lib/red-black-tree.rb
@@ -182,9 +182,11 @@ def delete! node
           end
 
           if node.distant_nephew && node.distant_nephew.valid? && node.distant_nephew.red?
-            case node.parent.colour
-            when Node::RED then node.sibling.red!
-            when Node::BLACK then node.sibling.black!
+            unless node.sibling.leaf?
+              case node.parent.colour
+              when Node::RED then node.sibling.red!
+              when Node::BLACK then node.sibling.black!
+              end
             end
             node.parent.black!
             node.distant_nephew.black!
@@ -194,15 +196,15 @@ def delete! node
           end
 
           if node.close_nephew && node.close_nephew.valid? && node.close_nephew.red?
-            node.sibling.red!
+            node.sibling.red! unless node.sibling.leaf?
             node.close_nephew.black!
             rotate_sub_tree! node.sibling, opp_direction
 
             next
           end
 
           if node.parent.red?
-            node.sibling.red!
+            node.sibling.red! unless node.sibling.leaf?
             node.parent.black!
 
             break