2024-08-12 v. 6.4.4: added "116. Populating Next Right Pointers in Each Node"

Author: fartem

README.md

@@ -509,3 +509,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 109. Convert Sorted List to Binary Search Tree                  | [Link](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/)                  | [Link](./lib/medium/109_convert_sorted_list_to_binary_search_tree.rb)                  |
 | 113. Path Sum II                                                | [Link](https://leetcode.com/problems/path-sum-ii/)                                                | [Link](./lib/medium/113_path_sum_ii.rb)                                                |
 | 114. Flatten Binary Tree to Linked List                         | [Link](https://leetcode.com/problems/flatten-binary-tree-to-linked-list/)                         | [Link](./lib/medium/114_flatten_binary_tree_to_linked_list.rb)                         |
+| 116. Populating Next Right Pointers in Each Node                | [Link](https://leetcode.com/problems/populating-next-right-pointers-in-each-node/)                | [Link](./lib/medium/116_populating_next_right_pointers_in_each_node.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 = '6.4.3.1'
+  s.version = '6.4.4'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/common/next_tree_node.rb

@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+# NextTreeNode implementation for this project
+class NextTreeNode
+  attr_accessor :val, :left, :right, :next
+
+  # @param {Integer} val
+  # @param {NextTreeNode} left
+  # @param {NextTreeNode} right
+  # @param {NextTreeNode} nxt
+  def initialize(val, left = nil, right = nil, nxt = nil)
+    @val = val
+    @left = left
+    @right = right
+    @next = nxt
+  end
+
+  # @param {NextTreeNode} n1
+  # @param {NextTreeNode} n2
+  # @return {Boolean}
+  def self.are_equals(n1, n2)
+    if n1 && n2
+      return false unless n1.val == n2.val && n1.next == n2.next
+
+      return are_equals(n1.left, n2.left) && are_equals(n1.right, n2.right)
+    end
+
+    n1.nil? && n2.nil?
+  end
+
+  # @param {NextTreeNode} other
+  # @return {Boolean}
+  def ==(other)
+    return false unless other.is_a?(::NextTreeNode)
+
+    val == other.val &&
+      left == other.left &&
+      right == other.right &&
+      self.next == other.next
+  end
+
+  # @return {Integer}
+  def hash
+    [val, left, right, nxt].hash
+  end
+end

lib/medium/116_populating_next_right_pointers_in_each_node.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require_relative '../common/next_tree_node'
+
+# https://leetcode.com/problems/populating-next-right-pointers-in-each-node/
+# @param {NextTreeNode} root
+# @return {NextTreeNode}
+def connect(root)
+  return unless root
+
+  if root.left
+    root.left.next = root.right
+    connect(root.left)
+    root.right.next = root.next ? root.next.left : nil
+    connect(root.right)
+  end
+
+  root
+end

test/common/test_binary_tree.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/next_tree_node'
+require_relative '../../lib/medium/116_populating_next_right_pointers_in_each_node'
+require 'minitest/autorun'
+
+class PopulatingNextRightPointersInEachNodeTest < ::Minitest::Test
+  def test_default
+    l3n4 = ::NextTreeNode.new(7)
+    l3n3 = ::NextTreeNode.new(6, nil, nil, l3n4)
+    l3n2 = ::NextTreeNode.new(5, nil, nil, l3n3)
+    l3n1 = ::NextTreeNode.new(4, nil, nil, l3n2)
+
+    l2n2 = ::NextTreeNode.new(3, l3n3, l3n4)
+    l2n1 = ::NextTreeNode.new(2, l3n1, l3n2, l2n2)
+
+    assert(
+      ::NextTreeNode.are_equals(
+        ::NextTreeNode.new(
+          1,
+          l2n1,
+          l2n2
+        ),
+        connect(
+          ::NextTreeNode.new(
+            1,
+            ::NextTreeNode.new(
+              2,
+              ::NextTreeNode.new(4),
+              ::NextTreeNode.new(5)
+            ),
+            ::NextTreeNode.new(
+              3,
+              ::NextTreeNode.new(6),
+              ::NextTreeNode.new(7)
+            )
+          )
+        )
+      )
+    )
+
+    assert(
+      ::NextTreeNode.are_equals(
+        nil,
+        connect(nil)
+      )
+    )
+  end
+end

test/common/test_linked_list.rb

@@ -4,6 +4,8 @@
 
 ::SimpleCov.use_merging(true)
 ::SimpleCov.start do
+  add_filter 'next_tree_node'
+
   add_filter '706_design_hashmap'
   add_filter '33_search_in_rotated_sorted_array'