2024-06-21 v. 5.9.4: added "2. Add Two Numbers"

README.md

@@ -454,3 +454,9 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 2540. Minimum Common Value                                         | [Link](https://leetcode.com/problems/minimum-common-value/)                                         | [Link](./lib/easy/2540_minimum_common_value.rb)                                         |
 | 2544. Alternating Digit Sum                                        | [Link](https://leetcode.com/problems/alternating-digit-sum/)                                        | [Link](./lib/easy/2544_alternating_digit_sum.rb)                                        |
 | 2549. Count Distinct Numbers on Board                              | [Link](https://leetcode.com/problems/count-distinct-numbers-on-board/)                              | [Link](./lib/easy/2549_count_distinct_numbers_on_board.rb)                              |
+
+### Medium
+
+| Name               | Link to LeetCode                                       | Link to solution                          |
+|--------------------|--------------------------------------------------------|-------------------------------------------|
+| 2. Add Two Numbers | [Link](https://leetcode.com/problems/add-two-numbers/) | [Link](./lib/medium/2_add_two_numbers.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 = '5.9.3'
+  s.version = '5.9.4'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[bin/leetcode-ruby README.md LICENSE]
   s.executable = 'leetcode-ruby'

lib/medium/2_add_two_numbers.rb

@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+require_relative '../common/linked_list'
+
+# https://leetcode.com/problems/add-two-numbers/
+# @param {ListNode} l1
+# @param {ListNode} l2
+# @return {ListNode}
+def add_two_numbers(l1, l2)
+  sum = ::ListNode.new
+  p = sum
+  add = 0
+  while !l1.nil? && !l2.nil?
+    a = l1.val
+    b = l2.val
+    s = a + b + add
+
+    if s > 9
+      s -= 10
+      add = 1
+    else
+      add = 0
+    end
+
+    p.next = ::ListNode.new(s)
+    p = p.next
+    l1 = l1.next
+    l2 = l2.next
+  end
+
+  if !l1.nil?
+    until l1.nil?
+      s = l1.val + add
+
+      if s > 9
+        s -= 10
+        add = 1
+      else
+        add = 0
+      end
+
+      p&.next = ::ListNode.new(s)
+      p = p&.next
+      l1 = l1.next
+    end
+  elsif !l2.nil?
+    until l2.nil?
+      s = l2.val + add
+
+      if s > 9
+        s -= 10
+        add = 1
+      else
+        add = 0
+      end
+
+      p&.next = ::ListNode.new(s)
+      p = p&.next
+      l2 = l2.next
+    end
+  end
+
+  p&.next = ::ListNode.new(1) if add == 1
+
+  sum.next
+end

test/medium/test_2_add_two_numbers.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/2_add_two_numbers'
+require_relative '../../lib/common/linked_list'
+require 'minitest/autorun'
+
+class AddTwoNumbersTest < ::Minitest::Test
+  def test_default
+    assert(
+      ::ListNode.are_equals(
+        ::ListNode.from_array([7, 0, 8]),
+        add_two_numbers(
+          ::ListNode.from_array([2, 4, 3]),
+          ::ListNode.from_array([5, 6, 4])
+        )
+      )
+    )
+    assert(
+      ::ListNode.from_array([0]),
+      add_two_numbers(
+        ::ListNode.from_array([0]),
+        ::ListNode.from_array([0])
+      )
+    )
+    assert(
+      ::ListNode.from_array([8, 9, 9, 9, 0, 0, 0, 1]),
+      add_two_numbers(
+        ::ListNode.from_array([9, 9, 9, 9, 9, 9, 9]),
+        ::ListNode.from_array([9, 9, 9, 9])
+      )
+    )
+  end
+
+  def test_additional
+    assert(
+      ::ListNode.from_array([8, 9, 9, 9, 0, 0, 0]),
+      add_two_numbers(
+        ::ListNode.from_array([9, 9, 9, 9, 9, 9, 2]),
+        ::ListNode.from_array([9, 9, 9, 9])
+      )
+    )
+    assert(
+      ::ListNode.from_array([8, 9, 9, 9, 0, 0, 0]),
+      add_two_numbers(
+        ::ListNode.from_array([9, 9, 9, 9]),
+        ::ListNode.from_array([9, 9, 9, 9, 9, 9, 2])
+      )
+    )
+  end
+end