2024-12-18 v. 7.3.9: added "654. Maximum Binary Tree"

Author: fartem

README.md

@@ -603,3 +603,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 647. Palindromic Substrings                                     | [Link](https://leetcode.com/problems/palindromic-substrings/)                                     | [Link](./lib/medium/647_palindromic_substrings.rb)                                     | [Link](./test/medium/test_647_palindromic_substrings.rb)                                     |
 | 648. Replace Words                                              | [Link](https://leetcode.com/problems/replace-words/)                                              | [Link](./lib/medium/648_replace_words.rb)                                              | [Link](./test/medium/test_648_replace_words.rb)                                              |
 | 652. Find Duplicate Subtrees                                    | [Link](https://leetcode.com/problems/find-duplicate-subtrees/)                                    | [Link](./lib/medium/652_find_duplicate_subtrees.rb)                                    | [Link](./test/medium/test_652_find_duplicate_subtrees.rb)                                    |
+| 654. Maximum Binary Tree                                        | [Link](https://leetcode.com/problems/maximum-binary-tree/)                                        | [Link](./lib/medium/654_maximum_binary_tree.rb)                                        | [Link](./test/medium/test_654_maximum_binary_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 = '7.3.8'
+  s.version = '7.3.9'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/common/binary_tree.rb

@@ -18,11 +18,13 @@ def initialize(val = 0, left = nil, right = nil)
   # @return {Boolean}
   def self.are_equals(curr, other)
     return true if !curr && !other
+
     return false if !curr || !other
 
     curr_eq = curr.val == other.val
     left_eq = are_equals(curr.left, other.left)
     right_eq = are_equals(curr.right, other.right)
+
     curr_eq && left_eq && right_eq
   end
 

lib/medium/654_maximum_binary_tree.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/maximum-binary-tree/
+# @param {Integer[]} nums
+# @return {TreeNode}
+def construct_maximum_binary_tree(nums)
+  expand_construct_maximum_binary_tree(nums, 0, nums.size)
+end
+
+private
+
+# @param {Integer[]} nums
+# @param {Integer} left
+# @param {Integer} right
+# @return {Boolean}
+def expand_construct_maximum_binary_tree(nums, left, right)
+  return if left == right
+
+  max = max_for_maximum_binary_tree(nums, left, right)
+  root = ::TreeNode.new(nums[max])
+  root.left = expand_construct_maximum_binary_tree(nums, left, max)
+  root.right = expand_construct_maximum_binary_tree(nums, max + 1, right)
+
+  root
+end
+
+# @param {Integer[]} nums
+# @param {Integer} left
+# @param {Integer} right
+# @return {Integer}
+def max_for_maximum_binary_tree(nums, left, right)
+  max = left
+  (left...right).each { |i| max = i if nums[max] < nums[i] }
+
+  max
+end

test/medium/test_654_maximum_binary_tree.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/654_maximum_binary_tree'
+require 'minitest/autorun'
+
+class MaximumBinaryTreeTest < ::Minitest::Test
+  def test_default_one
+    assert(
+      ::TreeNode.are_equals(
+        ::TreeNode.new(
+          6,
+          ::TreeNode.new(
+            3,
+            nil,
+            ::TreeNode.new(
+              2,
+              nil,
+              ::TreeNode.new(1)
+            )
+          ),
+          ::TreeNode.new(
+            5,
+            ::TreeNode.new(0),
+            nil
+          )
+        ),
+        construct_maximum_binary_tree(
+          [3, 2, 1, 6, 0, 5]
+        )
+      )
+    )
+  end
+
+  def test_default_two
+    assert(
+      ::TreeNode.are_equals(
+        ::TreeNode.new(
+          3,
+          nil,
+          ::TreeNode.new(
+            2,
+            nil,
+            ::TreeNode.new(1)
+          )
+        ),
+        construct_maximum_binary_tree(
+          [3, 2, 1]
+        )
+      )
+    )
+  end
+end