2024-07-02 v. 6.0.1: added "15. 3Sum"

Author: fartem

README.md

@@ -466,3 +466,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 8. String to Integer (atoi)                       | [Link](https://leetcode.com/problems/string-to-integer-atoi/)                         | [Link](./lib/medium/8_string_to_integer_atoi.rb)                         |
 | 11. Container With Most Water                     | [Link](https://leetcode.com/problems/container-with-most-water/)                      | [Link](./lib/medium/11_container_with_most_water.rb)                     |
 | 12. Integer to Roman                              | [Link](https://leetcode.com/problems/integer-to-roman/)                               | [Link](./lib/medium/12_integer_to_roman.rb)                              |
+| 15. 3Sum                                          | [Link](https://leetcode.com/problems/3sum/)                                           | [Link](./lib/medium/15_3sum.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 = '6.0.0'
+  s.version = '6.0.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[bin/leetcode-ruby README.md LICENSE]
   s.executable = 'leetcode-ruby'

lib/medium/15_3sum.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/3sum/
+# @param {Integer[]} nums
+# @return {Integer[][]}
+def three_sum(nums)
+  nums.sort!
+  result = []
+  (0...nums.length - 2).each do |i|
+    curr = nums[i]
+
+    next if i.positive? && curr == nums[i - 1]
+
+    rem = -curr
+    start = i + 1
+    en = nums.length - 1
+
+    while start < en
+      s = nums[start]
+      e = nums[en]
+
+      if s + e == rem
+        result << [curr, s, e]
+
+        start += 1 while start < en && nums[start] == nums[start + 1]
+        en -= 1 while start < en && nums[en] == nums[en - 1]
+
+        start += 1
+        en -= 1
+      elsif s + e > rem
+        en -= 1
+      else
+        start += 1
+      end
+    end
+  end
+
+  result
+end

test/medium/test_15_3sum.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/15_3sum'
+require 'minitest/autorun'
+
+class ThreeSumTest < ::Minitest::Test
+  def test_default
+    assert_equal([[-1, -1, 2], [-1, 0, 1]], three_sum([-1, 0, 1, 2, -1, -4]))
+    assert_equal([], three_sum([0, 1, 1]))
+    assert_equal([[0, 0, 0]], three_sum([0, 0, 0]))
+  end
+end