2025-01-23 v. 8.2.5: added "1026. Maximum Difference Between Node and Ancestor"

Author: fartem

README.md

@@ -657,6 +657,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 1008. Construct Binary Search Tree from Preorder Traversal       | [Link](https://leetcode.com/problems/construct-binary-search-tree-from-preorder-traversal/)        | [Link](./lib/medium/1008_construct_binary_search_tree_from_preorder_traversal.rb)       | [Link](./test/medium/test_1008_construct_binary_search_tree_from_preorder_traversal.rb)       |
 | 1019. Next Greater Node In Linked List                           | [Link](https://leetcode.com/problems/next-greater-node-in-linked-list/)                            | [Link](./lib/medium/1019_next_greater_node_in_linked_list.rb)                           | [Link](./test/medium/test_1019_next_greater_node_in_linked_list.rb)                           |
 | 1023. Camelcase Matching                                         | [Link](https://leetcode.com/problems/camelcase-matching/)                                          | [Link](./lib/medium/1023_camelcase_matching.rb)                                         | [Link](./test/medium/test_1023_camelcase_matching.rb)                                         |
+| 1026. Maximum Difference Between Node and Ancestor               | [Link](https://leetcode.com/problems/maximum-difference-between-node-and-ancestor/)                | [Link](./lib/medium/1026_maximum_difference_between_node_and_ancestor.rb)               | [Link](./test/medium/test_1026_maximum_difference_between_node_and_ancestor.rb)               |
 | 1400. Construct K Palindrome Strings                             | [Link](https://leetcode.com/problems/construct-k-palindrome-strings/)                              | [Link](./lib/medium/1400_construct_k_palindrome_strings.rb)                             | [Link](./test/medium/test_1400_construct_k_palindrome_strings.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)                                |

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 = '8.2.4'
+  s.version = '8.2.5'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/common/binary_tree.rb

@@ -28,6 +28,40 @@ def self.are_equals(curr, other)
     curr_eq && left_eq && right_eq
   end
 
+  # @param {Integer[]} nodes
+  # @return {TreeNode}
+  def self.build_tree(nodes)
+    return if nodes.empty?
+
+    root = ::TreeNode.new(nodes[0])
+    queue = [root]
+    i = 1
+
+    while i < nodes.length
+      current = queue.shift
+      next unless current
+
+      # Left child
+      if i < nodes.length && !nodes[i].nil?
+        current.left = ::TreeNode.new(nodes[i])
+
+        queue << current.left
+      end
+
+      i += 1
+
+      if i < nodes.length && !nodes[i].nil?
+        current.right = ::TreeNode.new(nodes[i])
+
+        queue << current.right
+      end
+
+      i += 1
+    end
+
+    root
+  end
+
   # @param {TreeNode} other
   # @return {Boolean}
   def ==(other)

lib/medium/1026_maximum_difference_between_node_and_ancestor.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/maximum-difference-between-node-and-ancestor/
+# @param [TreeNode] root
+# @return [Integer]
+def max_ancestor_diff(root)
+  calculate_max_ancestor_diff(root, root.val, root.val)
+end
+
+private
+
+# @param {TreeNode} node
+# @param {Integer} min
+# @param {Integer} max
+# @return {Integer}
+def calculate_max_ancestor_diff(node, min, max)
+  return 0 if node.nil?
+
+  min = [node.val, min].min
+  max = [node.val, max].max
+
+  left = calculate_max_ancestor_diff(node.left, min, max)
+  right = calculate_max_ancestor_diff(node.right, min, max)
+
+  [left, right, max - min].max
+end

test/medium/test_1026_maximum_difference_between_node_and_ancestor.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/1026_maximum_difference_between_node_and_ancestor'
+require 'minitest/autorun'
+
+class MaximumDifferenceBetweenNodeAndAncestorTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      7,
+      max_ancestor_diff(
+        ::TreeNode.build_tree(
+          [8, 3, 10, 1, 6, nil, 14, nil, nil, 4, 7, 13]
+        )
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      3,
+      max_ancestor_diff(
+        ::TreeNode.build_tree(
+          [1, nil, 2, nil, 0, 3]
+        )
+      )
+    )
+  end
+end