2025-01-06 v. 7.7.2: added "41. First Missing Positive"

Author: fartem

README.md

@@ -641,3 +641,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 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) |
 | 32. Longest Valid Parentheses                 | [Link](https://leetcode.com/problems/longest-valid-parentheses/)                 | [Link](./lib/hard/32_longest_valid_parentheses.rb)                 | [Link](./test/hard/test_32_longest_valid_parentheses.rb)                 |
+| 41. First Missing Positive                    | [Link](https://leetcode.com/problems/first-missing-positive/)                    | [Link](./lib/hard/41_first_missing_positive.rb)                    | [Link](./test/hard/test_41_first_missing_positive.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 = '7.7.1'
+  s.version = '7.7.2'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/hard/41_first_missing_positive.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/first-missing-positive/
+# @param {Integer[]} nums
+# @return {Integer}
+def first_missing_positive(nums)
+  result = 1
+  nums.sort.each { |num| result += 1 if result == num }
+
+  result
+end

test/hard/test_41_first_missing_positive.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/hard/41_first_missing_positive'
+require 'minitest/autorun'
+
+class FirstMissingPositiveTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      3,
+      first_missing_positive(
+        [1, 2, 0]
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      2,
+      first_missing_positive(
+        [3, 4, -1, 1]
+      )
+    )
+  end
+
+  def test_default_three
+    assert_equal(
+      1,
+      first_missing_positive(
+        [7, 8, 9, 11, 12]
+      )
+    )
+  end
+end