2025-03-14 v. 8.9.9: added "2096. Step-By-Step Directions From a Binary Tree Node to Another"

Author: fartem

README.md

@@ -732,6 +732,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 2074. Reverse Nodes in Even Length Groups                                           | [Link](https://leetcode.com/problems/reverse-nodes-in-even-length-groups/)                                           | [Link](./lib/medium/2074_reverse_nodes_in_even_length_groups.rb)                                           | [Link](./test/medium/test_2074_reverse_nodes_in_even_length_groups.rb)                                           |
 | 2091. Removing Minimum and Maximum From Array                                       | [Link](https://leetcode.com/problems/removing-minimum-and-maximum-from-array/)                                       | [Link](./lib/medium/2091_removing_minimum_and_maximum_from_array.rb)                                       | [Link](./test/medium/test_2091_removing_minimum_and_maximum_from_array.rb)                                       |
 | 2095. Delete the Middle Node of a Linked List                                       | [Link](https://leetcode.com/problems/delete-the-middle-node-of-a-linked-list/)                                       | [Link](./lib/medium/2095_delete_the_middle_node_of_a_linked_list.rb)                                       | [Link](./test/medium/test_2095_delete_the_middle_node_of_a_linked_list.rb)                                       |
+| 2096. Step-By-Step Directions From a Binary Tree Node to Another                    | [Link](https://leetcode.com/problems/step-by-step-directions-from-a-binary-tree-node-to-another/)                    | [Link](./lib/medium/2096_step_by_step_directions_from_a_binary_tree_node_to_another.rb)                    | [Link](./test/medium/test_2096_step_by_step_directions_from_a_binary_tree_node_to_another.rb)                    |
 | 2116. Check if a Parentheses String Can Be Valid                                    | [Link](https://leetcode.com/problems/check-if-a-parentheses-string-can-be-valid/)                                    | [Link](./lib/medium/2116_check_if_a_parentheses_string_can_be_valid.rb)                                    | [Link](./test/medium/test_2116_check_if_a_parentheses_string_can_be_valid.rb)                                    |
 | 2425. Bitwise XOR of All Pairings                                                   | [Link](https://leetcode.com/problems/bitwise-xor-of-all-pairings/)                                                   | [Link](./lib/medium/2425_bitwise_xor_of_all_pairings.rb)                                                   | [Link](./test/medium/test_2425_bitwise_xor_of_all_pairings.rb)                                                   |
 | 2429. Minimize XOR                                                                  | [Link](https://leetcode.com/problems/minimize-xor/)                                                                  | [Link](./lib/medium/2429_minimize_xor.rb)                                                                  | [Link](./test/medium/test_2429_minimize_xor.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 = '8.9.8'
+  s.version = '8.9.9'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/2096_step_by_step_directions_from_a_binary_tree_node_to_another.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/step-by-step-directions-from-a-binary-tree-node-to-another/
+# @param {TreeNode} root
+# @param {Integer} start_value
+# @param {Integer} dest_value
+# @return {String}
+def get_directions(root, start_value, dest_value)
+  find_path =
+    lambda { |node, target, path|
+      return false if node.nil?
+
+      path << node
+
+      return true if node.val == target
+
+      return true if find_path.call(node.left, target, path) || find_path.call(node.right, target, path)
+
+      path.pop
+
+      false
+    }
+
+  start_path = []
+  dest_path = []
+
+  find_path.call(root, start_value, start_path)
+  find_path.call(root, dest_value, dest_path)
+
+  lca = nil
+  [start_path.size, dest_path.size].min.times do |i|
+    break unless start_path[i] == dest_path[i]
+
+    lca = start_path[i]
+  end
+
+  start_to_lca = []
+  lca_to_dest = []
+
+  start_path.reverse.each_with_index do |node, _i|
+    break if node == lca
+
+    start_to_lca << 'U'
+  end
+
+  lca_index = dest_path.index(lca)
+  (lca_index...dest_path.size - 1).each do |i|
+    lca_to_dest << if dest_path[i].left == dest_path[i + 1]
+                     'L'
+                   else
+                     'R'
+                   end
+  end
+
+  (start_to_lca + lca_to_dest).join
+end

test/medium/test_2096_step_by_step_directions_from_a_binary_tree_node_to_another.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/2096_step_by_step_directions_from_a_binary_tree_node_to_another'
+require 'minitest/autorun'
+
+class StepByStepDirectionsFromABinaryTreeNodeToAnotherTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      'UURL',
+      get_directions(
+        ::TreeNode.build_tree(
+          [5, 1, 2, 3, nil, 6, 4]
+        ),
+        3,
+        6
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      'L',
+      get_directions(
+        ::TreeNode.build_tree(
+          [2, 1]
+        ),
+        2,
+        1
+      )
+    )
+  end
+end