2024-12-23 v. 7.4.5: added "687. Longest Univalue Path"

Author: fartem

README.md

@@ -609,3 +609,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 669. Trim a Binary Search Tree                                  | [Link](https://leetcode.com/problems/trim-a-binary-search-tree/)                                  | [Link](./lib/medium/669_trim_a_binary_search_tree.rb)                                  | [Link](./test/medium/test_669_trim_a_binary_search_tree.rb)                                  |
 | 677. Map Sum Pairs                                              | [Link](https://leetcode.com/problems/map-sum-pairs/)                                              | [Link](./lib/medium/677_map_sum_pairs.rb)                                              | [Link](./test/medium/test_677_map_sum_pairs.rb)                                              |
 | 678. Valid Parenthesis String                                   | [Link](https://leetcode.com/problems/valid-parenthesis-string/)                                   | [Link](./lib/medium/678_valid_parenthesis_string.rb)                                   | [Link](./test/medium/test_678_valid_parenthesis_string.rb)                                   |
+| 687. Longest Univalue Path                                      | [Link](https://leetcode.com/problems/longest-univalue-path/)                                      | [Link](./lib/medium/687_longest_univalue_path.rb)                                      | [Link](./test/medium/test_687_longest_univalue_path.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 = '7.4.4'
+  s.version = '7.4.5'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/687_longest_univalue_path.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/longest-univalue-path/
+# @param {TreeNode} root
+# @return {Integer}
+def longest_univalue_path(root)
+  @result = 0
+  find_path_for_longest_univalue_path(root)
+
+  @result
+end
+
+private
+
+# @param {TreeNode} node
+# @return {Integer}
+def find_path_for_longest_univalue_path(node)
+  return 0 unless node
+
+  arrow_left = 0
+  left = find_path_for_longest_univalue_path(node.left)
+  arrow_left += left + 1 if node.left && node.left.val == node.val
+
+  arrow_right = 0
+  right = find_path_for_longest_univalue_path(node.right)
+  arrow_right += right + 1 if node.right && node.right.val == node.val
+
+  @result = [@result, arrow_left + arrow_right].max
+
+  [arrow_left, arrow_right].max
+end

test/medium/test_687_longest_univalue_path.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/687_longest_univalue_path'
+require 'minitest/autorun'
+
+class ValidParenthesisStringTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      2,
+      longest_univalue_path(
+        ::TreeNode.new(
+          5,
+          ::TreeNode.new(
+            4,
+            ::TreeNode.new(1),
+            ::TreeNode.new(1)
+          ),
+          ::TreeNode.new(
+            5,
+            nil,
+            ::TreeNode.new(5)
+          )
+        )
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      2,
+      longest_univalue_path(
+        ::TreeNode.new(
+          1,
+          ::TreeNode.new(
+            4,
+            ::TreeNode.new(4),
+            ::TreeNode.new(4)
+          ),
+          ::TreeNode.new(
+            5,
+            nil,
+            ::TreeNode.new(5)
+          )
+        )
+      )
+    )
+  end
+end