Lowest Common Ancestor of a Binary Search Tree

Author: nch3ng

Lowest Common Ancestor of a Binary Search Tree/Solution.rb

@@ -0,0 +1,27 @@
+# Definition for a binary tree node.
+# class TreeNode
+#     attr_accessor :val, :left, :right
+#     def initialize(val)
+#         @val = val
+#         @left, @right = nil, nil
+#     end
+# end
+
+# @param {TreeNode} root
+# @param {TreeNode} p
+# @param {TreeNode} q
+# @return {TreeNode}
+def lowest_common_ancestor(root, p, q)
+    return root if root.nil?
+    
+    
+    if root.val > p.val && root.val > q.val
+        return lowest_common_ancestor(root.left, p, q)
+    end
+    
+    if root.val < p.val && root.val < q.val
+        return lowest_common_ancestor(root.right, p, q)
+    end
+    
+    return root
+end

README.md

@@ -15,6 +15,8 @@ Binary Tree Preorder Traversal
 Binary Tree Postorder Traversal  
 Serialize and Deserialize Binary Tree  
 Word Break  
-Binary Tree Paths
+Binary Tree Paths  
+Lowest Common Ancestor of a Binary Search Tree  
 
+  
 Until 12/2