2025-03-12 v. 8.9.3: added "2023. Number of Pairs of Strings With Concatenation Equal to Target"

Author: fartem

README.md

@@ -726,6 +726,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 1985. Find the Kth Largest Integer in the Array                                     | [Link](https://leetcode.com/problems/find-the-kth-largest-integer-in-the-array/)                                     | [Link](./lib/medium/1985_find_the_kth_largest_integer_in_the_array.rb)                                     | [Link](./test/medium/test_1985_find_the_kth_largest_integer_in_the_array.rb)                                     |
 | 1996. The Number of Weak Characters in the Game                                     | [Link](https://leetcode.com/problems/the-number-of-weak-characters-in-the-game/)                                     | [Link](./lib/medium/1996_the_number_of_weak_characters_in_the_game.rb)                                     | [Link](./test/medium/test_1996_the_number_of_weak_characters_in_the_game.rb)                                     |
 | 2007. Find Original Array From Doubled Array                                        | [Link](https://leetcode.com/problems/find-original-array-from-doubled-array/)                                        | [Link](./lib/medium/2007_find_original_array_from_doubled_array.rb)                                        | [Link](./test/medium/test_2007_find_original_array_from_doubled_array.rb)                                        |
+| 2023. Number of Pairs of Strings With Concatenation Equal to Target                 | [Link](https://leetcode.com/problems/number-of-pairs-of-strings-with-concatenation-equal-to-target/)                 | [Link](./lib/medium/2023_number_of_pairs_of_strings_with_concatenation_equal_to_target.rb)                 | [Link](./test/medium/test_2023_number_of_pairs_of_strings_with_concatenation_equal_to_target.rb)                 |
 | 2116. Check if a Parentheses String Can Be Valid                                    | [Link](https://leetcode.com/problems/check-if-a-parentheses-string-can-be-valid/)                                    | [Link](./lib/medium/2116_check_if_a_parentheses_string_can_be_valid.rb)                                    | [Link](./test/medium/test_2116_check_if_a_parentheses_string_can_be_valid.rb)                                    |
 | 2425. Bitwise XOR of All Pairings                                                   | [Link](https://leetcode.com/problems/bitwise-xor-of-all-pairings/)                                                   | [Link](./lib/medium/2425_bitwise_xor_of_all_pairings.rb)                                                   | [Link](./test/medium/test_2425_bitwise_xor_of_all_pairings.rb)                                                   |
 | 2429. Minimize XOR                                                                  | [Link](https://leetcode.com/problems/minimize-xor/)                                                                  | [Link](./lib/medium/2429_minimize_xor.rb)                                                                  | [Link](./test/medium/test_2429_minimize_xor.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 = '8.9.2'
+  s.version = '8.9.3'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/2023_number_of_pairs_of_strings_with_concatenation_equal_to_target.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/number-of-pairs-of-strings-with-concatenation-equal-to-target/
+# @param {String[]} nums
+# @param {String} target
+# @return {Integer}
+def num_of_pairs(nums, target)
+  count = 0
+  freq = ::Hash.new(0)
+
+  nums.each { |num| freq[num] += 1 }
+
+  nums.each do |s|
+    next unless target.start_with?(s)
+
+    remaining = target[s.size..]
+
+    next unless freq.key?(remaining)
+
+    count += freq[remaining]
+    count -= 1 if s == remaining
+  end
+
+  count
+end

test/medium/test_2023_number_of_pairs_of_strings_with_concatenation_equal_to_target.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/2023_number_of_pairs_of_strings_with_concatenation_equal_to_target'
+require 'minitest/autorun'
+
+class NumberOfPairsOfStringsWithConcatenationEqualToTargetTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      4,
+      num_of_pairs(
+        %w[777 7 77 77],
+        '7777'
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      2,
+      num_of_pairs(
+        %w[123 4 12 34],
+        '1234'
+      )
+    )
+  end
+
+  def test_default_three
+    assert_equal(
+      6,
+      num_of_pairs(
+        %w[1 1 1],
+        '11'
+      )
+    )
+  end
+end