Merge pull request #782 from fartem/450_Delete_Node_in_a_BST

2024-11-26 v. 7.1.1: added "450. Delete Node in a BST"

Author: fartem

.rubocop.yml

@@ -28,6 +28,8 @@ Bundler/GemComment:
 
 Metrics/AbcSize:
   Enabled: false
+Metrics/ClassLength:
+  Enabled: false
 Metrics/MethodLength:
   Enabled: false
 Metrics/CyclomaticComplexity:

README.md

@@ -576,3 +576,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 443. String Compression                                         | [Link](https://leetcode.com/problems/string-compression/)                                         | [Link](./lib/medium/443_string_compression.rb)                                         | [Link](./test/medium/test_443_string_compression.rb)                                         |
 | 445. Add Two Numbers II                                         | [Link](https://leetcode.com/problems/add-two-numbers-ii/)                                         | [Link](./lib/medium/445_add_two_numbers_ii.rb)                                         | [Link](./test/medium/test_445_add_two_numbers_ii.rb)                                         |
 | 449. Serialize and Deserialize BST                              | [Link](https://leetcode.com/problems/serialize-and-deserialize-bst/)                              | [Link](./lib/medium/449_serialize_and_deserialize_bst.rb)                              | [Link](./test/medium/test_449_serialize_and_deserialize_bst.rb)                              |
+| 450. Delete Node in a BST                                       | [Link](https://leetcode.com/problems/delete-node-in-a-bst/)                                       | [Link](./lib/medium/450_delete_node_in_a_bst.rb)                                       | [Link](./test/medium/test_450_delete_node_in_a_bst.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 = '7.1.0'
+  s.version = '7.1.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/common/binary_tree.rb

@@ -17,8 +17,8 @@ def initialize(val = 0, left = nil, right = nil)
   # @param {TreeNode} other
   # @return {Boolean}
   def self.are_equals(curr, other)
-    return true if curr.nil? && other.nil?
-    return false if curr.nil? || other.nil?
+    return true if !curr && !other
+    return false if !curr || !other
 
     curr_eq = curr.val == other.val
     left_eq = are_equals(curr.left, other.left)

lib/medium/450_delete_node_in_a_bst.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/delete-node-in-a-bst/
+# @param {TreeNode} root
+# @param {Integer} key
+# @return {TreeNode}
+def delete_node450(root, key)
+  return unless root
+
+  if key > root.val
+    root.right = delete_node450(root.right, key)
+  elsif key < root.val
+    root.left = delete_node450(root.left, key)
+  elsif !root.left && !root.right
+    root = nil
+  elsif root.right
+    root.val = successor(root)
+    root.right = delete_node450(root.right, root.val)
+  else
+    root.val = predecessor(root)
+    root.left = delete_node450(root.left, root.val)
+  end
+
+  root
+end
+
+private
+
+# @param {TreeNode} node
+# @return {Integer}
+def successor(node)
+  node = node.right
+  node = node.left while node.left
+
+  node.val
+end
+
+# @param {TreeNode} node
+# @return {Integer}
+def predecessor(node)
+  node = node.left
+  node = node.right while node.right
+
+  node.val
+end

test/medium/test_450_delete_node_in_a_bst.rb

@@ -0,0 +1,128 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/450_delete_node_in_a_bst'
+require 'minitest/autorun'
+
+class DeleteNodeInABSTTest < ::Minitest::Test
+  def test_default_one
+    assert(
+      ::TreeNode.are_equals(
+        ::TreeNode.new(
+          5,
+          ::TreeNode.new(
+            4,
+            ::TreeNode.new(2),
+            nil
+          ),
+          ::TreeNode.new(
+            6,
+            nil,
+            ::TreeNode.new(7)
+          )
+        ),
+        delete_node450(
+          ::TreeNode.new(
+            5,
+            ::TreeNode.new(
+              3,
+              ::TreeNode.new(2),
+              ::TreeNode.new(4)
+            ),
+            ::TreeNode.new(
+              6,
+              nil,
+              ::TreeNode.new(7)
+            )
+          ),
+          3
+        )
+      )
+    )
+  end
+
+  def test_default_two
+    assert(
+      ::TreeNode.are_equals(
+        ::TreeNode.new(
+          5,
+          ::TreeNode.new(
+            2,
+            nil,
+            ::TreeNode.new(4)
+          ),
+          ::TreeNode.new(
+            6,
+            nil,
+            ::TreeNode.new(7)
+          )
+        ),
+        delete_node450(
+          ::TreeNode.new(
+            5,
+            ::TreeNode.new(
+              2,
+              nil,
+              ::TreeNode.new(4)
+            ),
+            ::TreeNode.new(
+              6,
+              nil,
+              ::TreeNode.new(7)
+            )
+          ),
+          0
+        )
+      )
+    )
+  end
+
+  def test_default_three
+    assert(
+      ::TreeNode.are_equals(
+        nil,
+        delete_node450(
+          nil,
+          0
+        )
+      )
+    )
+  end
+
+  def test_additional_one
+    assert(
+      ::TreeNode.are_equals(
+        ::TreeNode.new(
+          10,
+          ::TreeNode.new(10),
+          ::TreeNode.new(10)
+        ),
+        delete_node450(
+          ::TreeNode.new(
+            10,
+            ::TreeNode.new(10),
+            ::TreeNode.new(10)
+          ),
+          20
+        )
+      )
+    )
+  end
+
+  def test_additional_two
+    assert(
+      ::TreeNode.are_equals(
+        ::TreeNode.new(10),
+        delete_node450(
+          ::TreeNode.new(
+            8,
+            ::TreeNode.new(10),
+            nil
+          ),
+          8
+        )
+      )
+    )
+  end
+end