From a2d1d55906c9e449f16e600894c9f65f8ee4f053 Mon Sep 17 00:00:00 2001
From: fartem <jaman.smlnsk@gmail.com>
Date: Wed, 4 Sep 2024 08:55:59 +0300
Subject: [PATCH] 2024-09-04 v. 6.6.2: added "173. Binary Search Tree Iterator"

---
 README.md                                     |  1 +
 leetcode-ruby.gemspec                         |  2 +-
 lib/medium/173_binary_search_tree_iterator.rb | 35 +++++++++++++++++++
 .../test_173_binary_search_tree_iterator.rb   | 35 +++++++++++++++++++
 4 files changed, 72 insertions(+), 1 deletion(-)
 create mode 100644 lib/medium/173_binary_search_tree_iterator.rb
 create mode 100644 test/medium/test_173_binary_search_tree_iterator.rb

diff --git a/README.md b/README.md
index ec7d66b..fc5bf1f 100644
--- a/README.md
+++ b/README.md
@@ -527,3 +527,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 155. Min Stack                                                  | [Link](https://leetcode.com/problems/min-stack/)                                                  | [Link](./lib/medium/155_min_stack.rb)                                                  | [Link](./test/medium/test_155_min_stack.rb)                                                  |
 | 165. Compare Version Numbers                                    | [Link](https://leetcode.com/problems/compare-version-numbers/)                                    | [Link](./lib/medium/165_compare_version_numbers.rb)                                    | [Link](./test/medium/test_165_compare_version_numbers.rb)                                    |
 | 167. Two Sum II - Input Array Is Sorted                         | [Link](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/)                           | [Link](./lib/medium/167_two_sum_ii_input_array_is_sorted.rb)                           | [Link](./test/medium/test_167_two_sum_ii_input_array_is_sorted.rb)                           |
+| 173. Binary Search Tree Iterator                                | [Link](https://leetcode.com/problems/binary-search-tree-iterator/)                                | [Link](./lib/medium/173_binary_search_tree_iterator.rb)                                | [Link](./test/medium/test_173_binary_search_tree_iterator.rb)                                |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 0e78c0e..1bb1472 100644
--- a/leetcode-ruby.gemspec
+++ b/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 = '6.6.1'
+  s.version = '6.6.2'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/173_binary_search_tree_iterator.rb b/lib/medium/173_binary_search_tree_iterator.rb
new file mode 100644
index 0000000..b04f123
--- /dev/null
+++ b/lib/medium/173_binary_search_tree_iterator.rb
@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/binary-search-tree-iterator/
+class BSTIterator
+  # @param {TreeNode} root
+  def initialize(root)
+    @values = []
+    @pointer = 0
+
+    traverse173(root) if root
+  end
+
+  # @return {Integer}
+  def next
+    value = @values[@pointer]
+    @pointer += 1
+
+    value
+  end
+
+  # @return {Boolean}
+  def has_next = @values.size > @pointer
+
+  private
+
+  # @param {TreeNode} node
+  # @return {Void}
+  def traverse173(node)
+    return unless node
+
+    traverse173(node.left)
+    @values << node.val
+    traverse173(node.right)
+  end
+end
diff --git a/test/medium/test_173_binary_search_tree_iterator.rb b/test/medium/test_173_binary_search_tree_iterator.rb
new file mode 100644
index 0000000..dab88a8
--- /dev/null
+++ b/test/medium/test_173_binary_search_tree_iterator.rb
@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/173_binary_search_tree_iterator'
+require 'minitest/autorun'
+
+class BinarySearchTreeIndicatorTest < ::Minitest::Test
+  def test_default_one
+    bst_iterator = ::BSTIterator.new(
+      ::TreeNode.new(
+        7,
+        ::TreeNode.new(3),
+        ::TreeNode.new(
+          15,
+          ::TreeNode.new(9),
+          ::TreeNode.new(20)
+        )
+      )
+    )
+
+    assert_equal(3, bst_iterator.next)
+    assert_equal(7, bst_iterator.next)
+    assert(bst_iterator.has_next)
+
+    assert_equal(9, bst_iterator.next)
+    assert(bst_iterator.has_next)
+
+    assert_equal(15, bst_iterator.next)
+    assert(bst_iterator.has_next)
+
+    assert_equal(20, bst_iterator.next)
+    assert(!bst_iterator.has_next)
+  end
+end