2025-01-03 v. 7.6.8: added "30. Substring with Concatenation of All Words"

Author: fartem

README.md

@@ -631,9 +631,10 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 
 ### Hard
 
-| Name                            | Link to LeetCode                                                   | Link to solution                                     | Link to tests                                              |
-| ------------------------------- | ------------------------------------------------------------------ | ---------------------------------------------------- | ---------------------------------------------------------- |
-| 4. Median of Two Sorted Arrays  | [Link](https://leetcode.com/problems/median-of-two-sorted-arrays/) | [Link](./lib/hard/4_median_of_two_sorted_arrays.rb)  | [Link](./test/hard/test_4_median_of_two_sorted_arrays.rb)  |
-| 10. Regular Expression Matching | [Link](https://leetcode.com/problems/regular-expression-matching/) | [Link](./lib/hard/10_regular_expression_matching.rb) | [Link](./test/hard/test_10_regular_expression_matching.rb) |
-| 23. Merge k Sorted Lists        | [Link](https://leetcode.com/problems/merge-k-sorted-lists/)        | [Link](./lib/hard/23_merge_k_sorted_lists.rb)        | [Link](./test/hard/test_23_merge_k_sorted_lists.rb)        |
-| 25. Reverse Nodes in k-Group    | [Link](https://leetcode.com/problems/reverse-nodes-in-k-group/)    | [Link](./lib/hard/25_reverse_nodes_in_k_group.rb)    | [Link](./test/hard/test_25_reverse_nodes_in_k_group.rb)    |
+| Name                                          | Link to LeetCode                                                                 | Link to solution                                                   | Link to tests                                                            |
+| --------------------------------------------- | -------------------------------------------------------------------------------- | ------------------------------------------------------------------ | ------------------------------------------------------------------------ |
+| 4. Median of Two Sorted Arrays                | [Link](https://leetcode.com/problems/median-of-two-sorted-arrays/)               | [Link](./lib/hard/4_median_of_two_sorted_arrays.rb)                | [Link](./test/hard/test_4_median_of_two_sorted_arrays.rb)                |
+| 10. Regular Expression Matching               | [Link](https://leetcode.com/problems/regular-expression-matching/)               | [Link](./lib/hard/10_regular_expression_matching.rb)               | [Link](./test/hard/test_10_regular_expression_matching.rb)               |
+| 23. Merge k Sorted Lists                      | [Link](https://leetcode.com/problems/merge-k-sorted-lists/)                      | [Link](./lib/hard/23_merge_k_sorted_lists.rb)                      | [Link](./test/hard/test_23_merge_k_sorted_lists.rb)                      |
+| 25. Reverse Nodes in k-Group                  | [Link](https://leetcode.com/problems/reverse-nodes-in-k-group/)                  | [Link](./lib/hard/25_reverse_nodes_in_k_group.rb)                  | [Link](./test/hard/test_25_reverse_nodes_in_k_group.rb)                  |
+| 30. Substring with Concatenation of All Words | [Link](https://leetcode.com/problems/substring-with-concatenation-of-all-words/) | [Link](./lib/hard/30_substring_with_concatenation_of_all_words.rb) | [Link](./test/hard/test_30_substring_with_concatenation_of_all_words.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 = '7.6.7'
+  s.version = '7.6.8'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/hard/30_substring_with_concatenation_of_all_words.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/substring-with-concatenation-of-all-words/
+# @param {String} s
+# @param {String[]} words
+# @return {Integer[]}
+def find_substring(s, words)
+  @word_count = words.tally
+  @k = words.size
+  @word_size = words[0].size
+  @substring_size = @word_size * @k
+
+  result = []
+  (0..(s.size - @substring_size)).each do |i|
+    result << i if check_for_find_substring(i, s)
+  end
+
+  result
+end
+
+private
+
+# @param {Integer} i
+# @param {String} s
+# @return {Boolean}
+def check_for_find_substring(i, s)
+  rem = @word_count.clone
+  words_used = 0
+  (i...(i + @substring_size)).step(@word_size).each do |j|
+    sub = s[j...(j + @word_size)]
+
+    break if rem.fetch(sub, 0).zero?
+
+    rem[sub] = rem[sub] - 1
+    words_used += 1
+  end
+
+  words_used == @k
+end

test/hard/test_30_substring_with_concatenation_of_all_words.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/hard/30_substring_with_concatenation_of_all_words'
+require 'minitest/autorun'
+
+class SubstringWithConcatenationOfAllWordsTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      [0, 9],
+      find_substring(
+        'barfoothefoobarman',
+        %w[foo bar]
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      [],
+      find_substring(
+        'wordgoodgoodgoodbestword',
+        %w[word good best word]
+      )
+    )
+  end
+
+  def test_default_three
+    assert_equal(
+      [6, 9, 12],
+      find_substring(
+        'barfoofoobarthefoobarman',
+        %w[bar foo the]
+      )
+    )
+  end
+end