2024-12-18 v. 7.3.8: added "652. Find Duplicate Subtrees"

Author: fartem

README.md

@@ -602,3 +602,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 641. Design Circular Deque                                      | [Link](https://leetcode.com/problems/design-circular-deque/)                                      | [Link](./lib/medium/641_design_circular_deque.rb)                                      | [Link](./test/medium/test_641_design_circular_deque.rb)                                      |
 | 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)                                    |

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 = '7.3.7'
+  s.version = '7.3.8'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/652_find_duplicate_subtrees.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/find-duplicate-subtrees/
+# @param {TreeNode} root
+# @return {TreeNode[]}
+def find_duplicate_subtrees(root)
+  @duplicates = ::Set.new
+  @nodes = {}
+
+  traverse_for_find_duplicate_subtrees(root)
+
+  @duplicates.to_a
+end
+
+private
+
+# @param {TreeNode} node
+# @return {String}
+def traverse_for_find_duplicate_subtrees(node)
+  return '' unless node
+
+  left = traverse_for_find_duplicate_subtrees(node.left)
+  right = traverse_for_find_duplicate_subtrees(node.right)
+  curr = "#{left} #{right} #{node.val}"
+
+  if @nodes.include?(curr)
+    @duplicates << @nodes[curr]
+  else
+    @nodes[curr] = node
+  end
+
+  curr
+end

test/medium/test_652_find_duplicate_subtrees.rb

@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/652_find_duplicate_subtrees'
+require 'minitest/autorun'
+
+class FindDuplicateSubtreesTest < ::Minitest::Test
+  def test_default_one
+    result = find_duplicate_subtrees(
+      ::TreeNode.new(
+        1,
+        ::TreeNode.new(
+          2,
+          ::TreeNode.new(4),
+          nil
+        ),
+        ::TreeNode.new(
+          3,
+          ::TreeNode.new(
+            2,
+            ::TreeNode.new(4),
+            nil
+          ),
+          ::TreeNode.new(4)
+        )
+      )
+    )
+
+    [
+      ::TreeNode.new(4),
+      ::TreeNode.new(
+        2,
+        ::TreeNode.new(4),
+        nil
+      )
+    ].each_with_index do |node, index|
+      assert(
+        ::TreeNode.are_equals(
+          node,
+          result[index]
+        )
+      )
+    end
+  end
+
+  def test_default_two
+    result = find_duplicate_subtrees(
+      ::TreeNode.new(
+        2,
+        ::TreeNode.new(1),
+        ::TreeNode.new(1)
+      )
+    )
+
+    [
+      ::TreeNode.new(1)
+    ].each_with_index do |node, index|
+      assert(
+        ::TreeNode.are_equals(
+          node,
+          result[index]
+        )
+      )
+    end
+  end
+
+  def test_default_three
+    result = find_duplicate_subtrees(
+      ::TreeNode.new(
+        2,
+        ::TreeNode.new(
+          2,
+          ::TreeNode.new(3),
+          nil
+        ),
+        ::TreeNode.new(
+          2,
+          ::TreeNode.new(3),
+          nil
+        )
+      )
+    )
+
+    [
+      ::TreeNode.new(3),
+      ::TreeNode.new(
+        2,
+        ::TreeNode.new(3),
+        nil
+      )
+    ].each_with_index do |node, index|
+      assert(
+        ::TreeNode.are_equals(
+          node,
+          result[index]
+        )
+      )
+    end
+  end
+end