From dcd7906fade8baa6577bb2cedd4f16db0feff576 Mon Sep 17 00:00:00 2001
From: fartem <jaman.smlnsk@gmail.com>
Date: Mon, 21 Oct 2024 13:24:05 +0300
Subject: [PATCH] 2024-10-21 v. 6.8.5: added "318. Maximum Product of Word
 Lengths"

---
 README.md                                     |  1 +
 leetcode-ruby.gemspec                         |  2 +-
 .../318_maximum_product_of_word_lengths.rb    | 30 ++++++++++++++++
 ...est_318_maximum_product_of_word_lengths.rb | 34 +++++++++++++++++++
 4 files changed, 66 insertions(+), 1 deletion(-)
 create mode 100644 lib/medium/318_maximum_product_of_word_lengths.rb
 create mode 100644 test/medium/test_318_maximum_product_of_word_lengths.rb

diff --git a/README.md b/README.md
index a0136548..a35156c3 100644
--- a/README.md
+++ b/README.md
@@ -550,3 +550,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 300. Longest Increasing Subsequence                             | [Link](https://leetcode.com/problems/longest-increasing-subsequence/)                             | [Link](./lib/medium/300_longest_increasing_subsequence.rb)                             | [Link](./test/medium/test_300_longest_increasing_subsequence.rb)                             |
 | 304. Range Sum Query 2D - Immutable                             | [Link](https://leetcode.com/problems/range-sum-query-2d-immutable/)                               | [Link](./lib/medium/304_range_sum_query_2d_immutable.rb)                               | [Link](./test/medium/test_304_range_sum_query_2d_immutable.rb)                               |
 | 316. Remove Duplicate Letters                                   | [Link](https://leetcode.com/problems/remove-duplicate-letters/)                                   | [Link](./lib/medium/316_remove_duplicate_letters.rb)                                   | [Link](./test/medium/test_316_remove_duplicate_letters.rb)                                   |
+| 318. Maximum Product of Word Lengths                            | [Link](https://leetcode.com/problems/maximum-product-of-word-lengths/)                            | [Link](./lib/medium/318_maximum_product_of_word_lengths.rb)                            | [Link](./test/medium/test_318_maximum_product_of_word_lengths.rb)                            |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 872f1752..63cdd114 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 = '6.8.4'
+  s.version = '6.8.5'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/318_maximum_product_of_word_lengths.rb b/lib/medium/318_maximum_product_of_word_lengths.rb
new file mode 100644
index 00000000..d5ee4d17
--- /dev/null
+++ b/lib/medium/318_maximum_product_of_word_lengths.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/maximum-product-of-word-lengths/
+# @param {String[]} words
+# @return {Integer}
+def max_product318(words)
+  result = 0
+  letters = ::Hash.new { |hash, key| hash[key] = ::Array.new(26, 0) }
+  words.each { |word| word.each_char { |char| letters[word][char.ord - 97] += 1 } }
+  words.each_with_index do |word, i|
+    w_letters = letters[word]
+    words.each_with_index do |candidate, k|
+      next if k == i
+
+      c_letters = letters[candidate]
+      correct = true
+      w_letters.each_with_index do |w_letter, m|
+        next unless w_letter != 0 && c_letters[m] != 0
+
+        correct = false
+
+        break
+      end
+
+      result = [result, word.length * candidate.length].max if correct
+    end
+  end
+
+  result
+end
diff --git a/test/medium/test_318_maximum_product_of_word_lengths.rb b/test/medium/test_318_maximum_product_of_word_lengths.rb
new file mode 100644
index 00000000..f625c431
--- /dev/null
+++ b/test/medium/test_318_maximum_product_of_word_lengths.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/318_maximum_product_of_word_lengths'
+require 'minitest/autorun'
+
+class MaximumProductOfWordLengthsTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      16,
+      max_product318(
+        %w[abcw baz foo bar xtfn abcdef]
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      4,
+      max_product318(
+        %w[a ab abc d cd bcd abcd]
+      )
+    )
+  end
+
+  def test_default_three
+    assert_equal(
+      0,
+      max_product318(
+        %w[a aa aaa aaaa]
+      )
+    )
+  end
+end