diff --git a/README.md b/README.md
index 4b229f95..1745fdfb 100644
--- a/README.md
+++ b/README.md
@@ -625,6 +625,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 814. Binary Tree Pruning                                        | [Link](https://leetcode.com/problems/binary-tree-pruning/)                                        | [Link](./lib/medium/814_binary_tree_pruning.rb)                                        | [Link](./test/medium/test_814_binary_tree_pruning.rb)                                        |
 | 817. Linked List Components                                     | [Link](https://leetcode.com/problems/linked-list-components/)                                     | [Link](./lib/medium/817_linked_list_components.rb)                                     | [Link](./test/medium/test_817_linked_list_components.rb)                                     |
 | 823. Binary Trees With Factors                                  | [Link](https://leetcode.com/problems/binary-trees-with-factors/)                                  | [Link](./lib/medium/823_binary_trees_with_factors.rb)                                  | [Link](./test/medium/test_823_binary_trees_with_factors.rb)                                  |
+| 841. Keys and Rooms                                             | [Link](https://leetcode.com/problems/keys-and-rooms/)                                             | [Link](./lib/medium/841_keys_and_rooms.rb)                                             | [Link](./test/medium/test_841_keys_and_rooms.rb)                                             |
 
 ### Hard
 
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 982b44da..9271b041 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 = '7.6.2'
+  s.version = '7.6.3'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/841_keys_and_rooms.rb b/lib/medium/841_keys_and_rooms.rb
new file mode 100644
index 00000000..a039b12e
--- /dev/null
+++ b/lib/medium/841_keys_and_rooms.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/keys-and-rooms/
+# @param {Integer[][]} rooms
+# @return {Boolean}
+def can_visit_all_rooms(rooms)
+  seen = ::Array.new(rooms.size, false)
+  seen[0] = true
+  stack = [0]
+
+  until stack.empty?
+    node = stack.delete_at(stack.size - 1)
+
+    rooms[node].each do |nxt|
+      next if seen[nxt]
+
+      seen[nxt] = true
+      stack << nxt
+    end
+  end
+
+  !seen.include?(false)
+end
diff --git a/test/medium/test_841_keys_and_rooms.rb b/test/medium/test_841_keys_and_rooms.rb
new file mode 100644
index 00000000..ee841890
--- /dev/null
+++ b/test/medium/test_841_keys_and_rooms.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/841_keys_and_rooms'
+require 'minitest/autorun'
+
+class KeysAndRoomsTest < ::Minitest::Test
+  def test_default_one
+    assert(
+      can_visit_all_rooms(
+        [
+          [1],
+          [2],
+          [3],
+          []
+        ]
+      )
+    )
+  end
+
+  def test_default_two
+    assert(
+      !can_visit_all_rooms(
+        [
+          [1, 3],
+          [3, 0, 1],
+          [2],
+          [0]
+        ]
+      )
+    )
+  end
+end