Merge pull request #741 from fartem/235_Lowest_Common_Ancestor_of_a_Binary_Search_Tree

2024-10-03 v. 6.7.4: added "235. Lowest Common Ancestor of a Binary Search Tree"

Author: fartem

README.md

@@ -539,3 +539,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 215. Kth Largest Element in an Array                            | [Link](https://leetcode.com/problems/kth-largest-element-in-an-array/)                            | [Link](./lib/medium/215_kth_largest_element_in_an_array.rb)                            | [Link](./test/medium/test_215_kth_largest_element_in_an_array.rb)                            |
 | 227. Basic Calculator II                                        | [Link](https://leetcode.com/problems/basic-calculator-ii/)                                        | [Link](./lib/medium/227_basic_calculator_ii.rb)                                        | [Link](./test/medium/test_227_basic_calculator_ii.rb)                                        |
 | 230. Kth Smallest Element in a BST                              | [Link](https://leetcode.com/problems/kth-smallest-element-in-a-bst/)                              | [Link](./lib/medium/230_kth_smallest_element_in_a_bst.rb)                              | [Link](./test/medium/test_230_kth_smallest_element_in_a_bst.rb)                              |
+| 235. Lowest Common Ancestor of a Binary Search Tree             | [Link](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/)             | [Link](./lib/medium/235_lowest_common_ancestor_of_a_binary_search_tree.rb)             | [Link](./test/medium/test_235_lowest_common_ancestor_of_a_binary_search_tree.rb)             |

leetcode-ruby.gemspec

@@ -5,7 +5,7 @@ require 'English'
 ::Gem::Specification.new do |s|
   s.required_ruby_version = '>= 3.0'
   s.name = 'leetcode-ruby'
-  s.version = '6.7.3'
+  s.version = '6.7.4'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/235_lowest_common_ancestor_of_a_binary_search_tree.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/
+# @param {TreeNode} root
+# @param {TreeNode} p
+# @param {TreeNode} q
+# @return {TreeNode}
+def lowest_common_ancestor(root, p, q)
+  node = root
+
+  while node
+    if p.val > node.val && q.val > node.val
+      node = node.right
+    elsif p.val < node.val && q.val < node.val
+      node = node.left
+    else
+      return node
+    end
+  end
+end

test/medium/test_235_lowest_common_ancestor_of_a_binary_search_tree.rb

@@ -0,0 +1,104 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/235_lowest_common_ancestor_of_a_binary_search_tree'
+require 'minitest/autorun'
+
+class LowestCommonAncestorOfABinarySearchTreeTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      6,
+      lowest_common_ancestor(
+        ::TreeNode.new(
+          6,
+          ::TreeNode.new(
+            2,
+            ::TreeNode.new(0),
+            ::TreeNode.new(
+              4,
+              ::TreeNode.new(3),
+              ::TreeNode.new(5)
+            )
+          ),
+          ::TreeNode.new(
+            8,
+            ::TreeNode.new(7),
+            ::TreeNode.new(9)
+          )
+        ),
+        ::TreeNode.new(2),
+        ::TreeNode.new(8)
+      ).val
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      2,
+      lowest_common_ancestor(
+        ::TreeNode.new(
+          6,
+          ::TreeNode.new(
+            2,
+            ::TreeNode.new(0),
+            ::TreeNode.new(
+              4,
+              ::TreeNode.new(3),
+              ::TreeNode.new(5)
+            )
+          ),
+          ::TreeNode.new(
+            8,
+            ::TreeNode.new(7),
+            ::TreeNode.new(9)
+          )
+        ),
+        ::TreeNode.new(2),
+        ::TreeNode.new(4)
+      ).val
+    )
+  end
+
+  def test_default_three
+    assert_equal(
+      2,
+      lowest_common_ancestor(
+        ::TreeNode.new(
+          2,
+          ::TreeNode.new(1),
+          nil
+        ),
+        ::TreeNode.new(2),
+        ::TreeNode.new(1)
+      ).val
+    )
+  end
+
+  def test_additional_one
+    assert_equal(
+      4,
+      lowest_common_ancestor(
+        ::TreeNode.new(
+          6,
+          ::TreeNode.new(
+            2,
+            ::TreeNode.new(0),
+            ::TreeNode.new(
+              4,
+              ::TreeNode.new(3),
+              ::TreeNode.new(5)
+            )
+          ),
+          ::TreeNode.new(
+            8,
+            ::TreeNode.new(7),
+            ::TreeNode.new(9)
+          )
+        ),
+        ::TreeNode.new(3),
+        ::TreeNode.new(5)
+      ).val
+    )
+  end
+end