Merge pull request #690 from fartem/95_Unique_Binary_Search_Trees_II

2024-07-26 v. 6.3.2: added "95. Unique Binary Search Trees II"

Author: fartem

README.md

@@ -497,3 +497,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 82. Remove Duplicates from Sorted List II                   | [Link](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/)                   | [Link](./lib/medium/82_remove_duplicates_from_sorted_list_ii.rb)                   |
 | 86. Partition List                                          | [Link](https://leetcode.com/problems/partition-list/)                                          | [Link](./lib/medium/86_partition_list.rb)                                          |
 | 92. Reverse Linked List II                                  | [Link](https://leetcode.com/problems/reverse-linked-list-ii/)                                  | [Link](./lib/medium/92_reverse_linked_list_ii.rb)                                  |
+| 95. Unique Binary Search Trees II                           | [Link](https://leetcode.com/problems/unique-binary-search-trees-ii/)                           | [Link](./lib/medium/95_unique_binary_search_trees_ii.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 = '6.3.1'
+  s.version = '6.3.2'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/95_unique_binary_search_trees_ii.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+require_relative '../common/binary_tree'
+
+# https://leetcode.com/problems/unique-binary-search-trees-ii/
+# @param {Integer} n
+# @return {TreeNode[]}
+def generate_trees(n)
+  generate95(1, n)
+end
+
+private
+
+# @param {Integer} i
+# @param {Integer} j
+# @return {TreeNode}
+def generate95(i, j)
+  nodes = []
+
+  if i > j
+    nodes << nil
+  else
+    (i..j).each do |mid|
+      left = generate95(i, mid - 1)
+      right = generate95(mid + 1, j)
+
+      left.each do |l|
+        right.each do |r|
+          node = ::TreeNode.new(mid)
+          node.left = l
+          node.right = r
+
+          nodes << node
+        end
+      end
+    end
+  end
+
+  nodes
+end

test/medium/test_95_unique_binary_search_trees_ii.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/95_unique_binary_search_trees_ii'
+require 'minitest/autorun'
+
+class UniqueBinarySearchTreesIITest < ::Minitest::Test
+  def test_default
+    assert_equal(
+      [
+        ::TreeNode.new(
+          1,
+          nil,
+          ::TreeNode.new(
+            2,
+            nil,
+            ::TreeNode.new(3)
+          )
+        ),
+        ::TreeNode.new(
+          1,
+          nil,
+          ::TreeNode.new(
+            3,
+            ::TreeNode.new(2),
+            nil
+          )
+        ),
+        ::TreeNode.new(
+          2,
+          ::TreeNode.new(1),
+          ::TreeNode.new(3)
+        ),
+        ::TreeNode.new(
+          3,
+          ::TreeNode.new(
+            1,
+            nil,
+            ::TreeNode.new(2)
+          ),
+          nil
+        ),
+        ::TreeNode.new(
+          3,
+          ::TreeNode.new(
+            2,
+            ::TreeNode.new(1),
+            nil
+          ),
+          nil
+        )
+      ],
+      generate_trees(3)
+    )
+    assert_equal(
+      [::TreeNode.new(1)],
+      generate_trees(1)
+    )
+  end
+end