2025-03-05 v. 8.8.3: added "1814. Count Nice Pairs in an Array"

Author: fartem

README.md

@@ -716,6 +716,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 1721. Swapping Nodes in a Linked List                                               | [Link](https://leetcode.com/problems/swapping-nodes-in-a-linked-list/)                                               | [Link](./lib/medium/1721_swapping_nodes_in_a_linked_list.rb)                                               | [Link](./test/medium/test_1721_swapping_nodes_in_a_linked_list.rb)                                               |
 | 1780. Check if Number is a Sum of Powers of Three                                   | [Link](https://leetcode.com/problems/check-if-number-is-a-sum-of-powers-of-three/)                                   | [Link](./lib/medium/1780_check_if_number_is_a_sum_of_powers_of_three.rb)                                   | [Link](./test/medium/test_1780_check_if_number_is_a_sum_of_powers_of_three.rb)                                   |
 | 1797. Design Authentication Manager                                                 | [Link](https://leetcode.com/problems/design-authentication-manager/)                                                 | [Link](./lib/medium/1797_design_authentication_manager.rb)                                                 | [Link](./test/medium/test_1797_design_authentication_manager.rb)                                                 |
+| 1814. Count Nice Pairs in an Array                                                  | [Link](https://leetcode.com/problems/count-nice-pairs-in-an-array/)                                                  | [Link](./lib/medium/1814_count_nice_pairs_in_an_array.rb)                                                  | [Link](./test/medium/test_1814_count_nice_pairs_in_an_array.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 = '8.8.2'
+  s.version = '8.8.3'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/1814_count_nice_pairs_in_an_array.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/count-nice-pairs-in-an-array/
+# @param {Integer[]} nums
+# @return {Integer}
+def count_nice_pairs(nums)
+  (0...nums.size).each { |i| nums[i] -= rev(nums[i]) }
+
+  count = {}
+  result = 0
+
+  nums.each do |num|
+    curr = count.fetch(num, 0)
+    result += curr
+    result %= 1_000_000_007
+
+    count[num] = curr + 1
+  end
+
+  result
+end
+
+private
+
+# @param {Integer} num
+# @return {Integer}
+def rev(num)
+  reversed = 0
+
+  until num.zero?
+    digit = num % 10
+    reversed = reversed * 10 + digit
+    num /= 10
+  end
+
+  reversed
+end

test/medium/test_1814_count_nice_pairs_in_an_array.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/1814_count_nice_pairs_in_an_array'
+require 'minitest/autorun'
+
+class CountNicePairsInAnArrayTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      2,
+      count_nice_pairs(
+        [42, 11, 1, 97]
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      4,
+      count_nice_pairs(
+        [13, 10, 35, 24, 76]
+      )
+    )
+  end
+end