2023-04-24 v. 0.0.7: added "21. Merge Two Sorted Lists"

Author: fartem

.rubocop.yml

@@ -23,6 +23,8 @@ Metrics/MethodLength:
   Enabled: false
 Metrics/CyclomaticComplexity:
   Enabled: false
+Metrics/PerceivedComplexity:
+  Enabled: false
 
 Naming/PredicateName:
   Enabled: false

README.md

@@ -12,10 +12,11 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 
 ### Easy
 
-| Name                      | Link to LeetCode                                             | Link to solution                               |
-|---------------------------|--------------------------------------------------------------|------------------------------------------------|
-| 1. Two Sum                | [Link](https://leetcode.com/problems/two-sum/)               | [Link](./lib/easy/1_two_sum.rb)                |
-| 9. Palindrome Number      | [Link](https://leetcode.com/problems/palindrome-number/)     | [Link](./lib/easy/9_palindrome_number.rb)      |
-| 13. Roman to Integer      | [Link](https://leetcode.com/problems/roman-to-integer/)      | [Link](./lib/easy/13_roman_to_integer.rb)      |
-| 14. Longest Common Prefix | [Link](https://leetcode.com/problems/longest-common-prefix/) | [Link](./lib/easy/14_longest_common_prefix.rb) |
-| 20. Valid Parentheses     | [Link](https://leetcode.com/problems/valid-parentheses/)     | [Link](./lib/easy/20_valid_parentheses.rb)     |
+| Name                       | Link to LeetCode                                              | Link to solution                                |
+|----------------------------|---------------------------------------------------------------|-------------------------------------------------|
+| 1. Two Sum                 | [Link](https://leetcode.com/problems/two-sum/)                | [Link](./lib/easy/1_two_sum.rb)                 |
+| 9. Palindrome Number       | [Link](https://leetcode.com/problems/palindrome-number/)      | [Link](./lib/easy/9_palindrome_number.rb)       |
+| 13. Roman to Integer       | [Link](https://leetcode.com/problems/roman-to-integer/)       | [Link](./lib/easy/13_roman_to_integer.rb)       |
+| 14. Longest Common Prefix  | [Link](https://leetcode.com/problems/longest-common-prefix/)  | [Link](./lib/easy/14_longest_common_prefix.rb)  |
+| 20. Valid Parentheses      | [Link](https://leetcode.com/problems/valid-parentheses/)      | [Link](./lib/easy/20_valid_parentheses.rb)      |
+| 21. Merge Two Sorted Lists | [Link](https://leetcode.com/problems/merge-two-sorted-lists/) | [Link](./lib/easy/21_merge_two_sorted_lists.rb) |

leetcode-ruby.gemspec

@@ -3,7 +3,7 @@ require 'English'
 ::Gem::Specification.new do |s|
   s.required_ruby_version = '>= 3.0'
   s.name = 'leetcode-ruby'
-  s.version = '0.0.6.4'
+  s.version = '0.0.7'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[bin/leetcode-ruby README.md LICENSE]
   s.executable = 'leetcode-ruby'

lib/common/linked_list.rb

@@ -0,0 +1,38 @@
+# LinkedList implementation for this project
+class ListNode
+  # @param val {Integer}
+  # @param _next {ListNode}
+  def initialize(val = 0, _next = nil)
+    @val = val
+    @next = _next
+  end
+
+  # @param values {Array}
+  def self.from_array(values)
+    return if values.empty?
+
+    list = ListNode.new(values.first)
+    head = list
+    values.drop(1).each do |value|
+      list.next = ListNode.new(value)
+      list = list.next
+    end
+    head
+  end
+
+  # @param other {LinkedList}
+  def ==(other)
+    are_equals(self, other)
+  end
+
+  # @param curr {ListNode}
+  # @param other {ListNode}
+  def are_equals(curr, other)
+    return true if curr.nil? && other.nil?
+    return false if curr.nil? || other.nil?
+
+    curr.val == other.val && are_equals(curr.next, other.next)
+  end
+
+  attr_accessor :val, :next
+end

lib/easy/21_merge_two_sorted_lists.rb

@@ -0,0 +1,28 @@
+require_relative '../common/linked_list'
+
+# @param {ListNode} list1
+# @param {ListNode} list2
+# @return {ListNode}
+def merge_two_lists(list1, list2)
+  return list1 if list2.nil?
+  return list2 if list1.nil?
+
+  min = list1.val > list2.val ? list2 : list1
+  max = list1.val > list2.val ? list1 : list2
+  result = ListNode.new(min.val)
+  min = min.next
+  head = result
+  while !min.nil? && !max.nil?
+    if min.val > max.val
+      result.next = ListNode.new(max.val)
+      max = max.next
+    else
+      result.next = ListNode.new(min.val)
+      min = min.next
+    end
+    result = result.next
+  end
+  result.next = min unless min.nil?
+  result.next = max unless max.nil?
+  head
+end

test/easy/test_21_merge_two_sorted_lists.rb

@@ -0,0 +1,19 @@
+require_relative '../../lib/easy/21_merge_two_sorted_lists'
+require 'minitest/autorun'
+
+class ValidParenthesesTest < Minitest::Test
+  def test_default
+    merge_two_lists(
+      ListNode.from_array([1, 2, 4]),
+      ListNode.from_array([1, 3, 4]),
+    ) == ListNode.from_array([1, 1, 2, 3, 4, 4])
+    merge_two_lists(
+      ListNode.from_array([]),
+      ListNode.from_array([]),
+    ) == nil
+    merge_two_lists(
+      ListNode.from_array([]),
+      ListNode.from_array([0]),
+    ) == ListNode.from_array([0])
+  end
+end