diff --git a/README.md b/README.md
index 70df239a..5e1d0488 100644
--- a/README.md
+++ b/README.md
@@ -595,3 +595,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 560. Subarray Sum Equals K                                      | [Link](https://leetcode.com/problems/subarray-sum-equals-k/)                                      | [Link](./lib/medium/560_subarray_sum_equals_k.rb)                                      | [Link](./test/medium/test_560_subarray_sum_equals_k.rb)                                      |
 | 581. Shortest Unsorted Continuous Subarray                      | [Link](https://leetcode.com/problems/shortest-unsorted-continuous-subarray/)                      | [Link](./lib/medium/581_shortest_unsorted_continuous_subarray.rb)                      | [Link](./test/medium/test_581_shortest_unsorted_continuous_subarray.rb)                      |
 | 606. Construct String from Binary Tree                          | [Link](https://leetcode.com/problems/construct-string-from-binary-tree/)                          | [Link](./lib/medium/606_construct_string_from_binary_tree.rb)                          | [Link](./test/medium/test_606_construct_string_from_binary_tree.rb)                          |
+| 609. Find Duplicate File in System                              | [Link](https://leetcode.com/problems/find-duplicate-file-in-system/)                              | [Link](./lib/medium/609_find_duplicate_file_in_system.rb)                              | [Link](./test/medium/test_609_find_duplicate_file_in_system.rb)                              |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 48912c2f..e9807e63 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 = '7.3.0'
+  s.version = '7.3.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/609_find_duplicate_file_in_system.rb b/lib/medium/609_find_duplicate_file_in_system.rb
new file mode 100644
index 00000000..397c89fc
--- /dev/null
+++ b/lib/medium/609_find_duplicate_file_in_system.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/find-duplicate-file-in-system/
+# @param {String[]} paths
+# @return {String[][]}
+def find_duplicate_paths(paths)
+  map = {}
+  paths.each do |path|
+    values = path.split
+    (1...values.size).each do |i|
+      name = values[i].split('(')
+      name[1] = name[1].gsub(/\)/, '')
+      arr = map.fetch(name[1], [])
+      arr << "#{values[0]}/#{name[0]}"
+      map[name[1]] = arr
+    end
+  end
+
+  result = []
+  map.each do |_, value|
+    next unless value.size > 1
+
+    result << value
+  end
+
+  result
+end
+
+# Map<String, List<String>> map = new HashMap<>();
+# for (String path : paths) {
+#     String[] values = path.split(" ");
+#     for (int i = 1; i < values.length; i++) {
+#         String[] name = values[i].split("\\(");
+#         name[1] = name[1].replace(")", "");
+#         List<String> list = map.getOrDefault(name[1], new ArrayList<>());
+#         list.add(values[0] + "/" + name[0]);
+#         map.put(name[1], list);
+#     }
+# }
+# List<List<String>> result = new ArrayList<>();
+# for (String key : map.keySet()) {
+#     if (map.get(key).size() > 1) {
+#         result.add(map.get(key));
+#     }
+# }
+# return result;
diff --git a/test/medium/test_609_find_duplicate_file_in_system.rb b/test/medium/test_609_find_duplicate_file_in_system.rb
new file mode 100644
index 00000000..924a20f4
--- /dev/null
+++ b/test/medium/test_609_find_duplicate_file_in_system.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/609_find_duplicate_file_in_system'
+require 'minitest/autorun'
+
+class FindDuplicateFileInSystemTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      [
+        [
+          'root/a/1.txt',
+          'root/c/3.txt'
+        ],
+        [
+          'root/a/2.txt',
+          'root/c/d/4.txt',
+          'root/4.txt'
+        ]
+      ],
+      find_duplicate_paths(
+        [
+          'root/a 1.txt(abcd) 2.txt(efgh)',
+          'root/c 3.txt(abcd)',
+          'root/c/d 4.txt(efgh)',
+          'root 4.txt(efgh)'
+        ]
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      [
+        [
+          'root/a/1.txt',
+          'root/c/3.txt'
+        ],
+        [
+          'root/a/2.txt',
+          'root/c/d/4.txt'
+        ]
+      ],
+      find_duplicate_paths(
+        [
+          'root/a 1.txt(abcd) 2.txt(efgh)',
+          'root/c 3.txt(abcd)',
+          'root/c/d 4.txt(efgh)'
+        ]
+      )
+    )
+  end
+end