2024-10-25 v. 6.8.9: added "341. Flatten Nested List Iterator"

Author: fartem

README.md

@@ -554,3 +554,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 328. Odd Even Linked List                                       | [Link](https://leetcode.com/problems/odd-even-linked-list/)                                       | [Link](./lib/medium/328_odd_even_linked_list.rb)                                       | [Link](./test/medium/test_328_odd_even_linked_list.rb)                                       |
 | 331. Verify Preorder Serialization of a Binary Tree             | [Link](https://leetcode.com/problems/verify-preorder-serialization-of-a-binary-tree/)             | [Link](./lib/medium/331_verify_preorder_serialization_of_a_binary_tree.rb)             | [Link](./test/medium/test_331_verify_preorder_serialization_of_a_binary_tree.rb)             |
 | 334. Increasing Triplet Subsequence                             | [Link](https://leetcode.com/problems/increasing-triplet-subsequence/)                             | [Link](./lib/medium/334_increasing_triplet_subsequence.rb)                             | [Link](./test/medium/test_334_increasing_triplet_subsequence.rb)                             |
+| 341. Flatten Nested List Iterator                               | [Link](https://leetcode.com/problems/flatten-nested-list-iterator/)                               | [Link](./lib/medium/341_flatten_nested_list_iterator.rb)                               | [Link](./test/medium/test_341_flatten_nested_list_iterator.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 = '6.8.8'
+  s.version = '6.8.9'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/341_flatten_nested_list_iterator.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/flatten-nested-list-iterator/
+class NestedIterator
+  # @param {NestedInteger[]} nested_list
+  def initialize(nested_list)
+    @values = []
+    @pointer = 0
+
+    prepare(nested_list)
+  end
+
+  # @return {Boolean}
+  def has_next = @pointer < @values.size
+
+  # @return {Integer}
+  def next
+    val = @values[@pointer]
+    @pointer += 1
+
+    val
+  end
+
+  private
+
+  # @param {NestedInteger[]} nested_list
+  # @return {Integer[]}
+  def prepare(nested_list)
+    nested_list.each do |num|
+      if num.is_integer
+        @values << num.get_integer
+      else
+        prepare(num.get_list)
+      end
+    end
+  end
+end
+
+# NestedInteger for NestedIterator
+class NestedInteger
+  # @param {NestenInteger} num
+  def initialize(num)
+    @num = num
+  end
+
+  # @return {Boolean}
+  def is_integer = @num.is_a?(::Integer)
+
+  # @return {Integer}
+  def get_integer = @num
+
+  # @return {Array}
+  def get_list = @num
+end

test/medium/test_341_flatten_nested_list_iterator.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/341_flatten_nested_list_iterator'
+require 'minitest/autorun'
+
+class FlattenNestedListIteratorTest < ::Minitest::Test
+  def test_default_one
+    nested_iterator = ::NestedIterator.new(
+      [
+        ::NestedInteger.new(
+          [
+            ::NestedInteger.new(1),
+            ::NestedInteger.new(1)
+          ]
+        ),
+        ::NestedInteger.new(2),
+        ::NestedInteger.new(
+          [
+            ::NestedInteger.new(1),
+            ::NestedInteger.new(1)
+          ]
+        )
+      ]
+    )
+
+    assert_equal(1, nested_iterator.next)
+    assert_equal(1, nested_iterator.next)
+    assert_equal(2, nested_iterator.next)
+    assert_equal(1, nested_iterator.next)
+    assert_equal(1, nested_iterator.next)
+
+    assert(!nested_iterator.has_next)
+  end
+
+  def test_default_two
+    # [1,[4,[6]]]
+
+    nested_iterator = ::NestedIterator.new(
+      [
+        ::NestedInteger.new(1),
+        ::NestedInteger.new(
+          [
+            ::NestedInteger.new(4),
+            ::NestedInteger.new(
+              [
+                ::NestedInteger.new(6)
+              ]
+            )
+          ]
+        )
+      ]
+    )
+
+    assert_equal(1, nested_iterator.next)
+    assert_equal(4, nested_iterator.next)
+    assert_equal(6, nested_iterator.next)
+
+    assert(!nested_iterator.has_next)
+  end
+end