Merge pull request #100 from fartem/415_Add_Strings

2023-06-13 v. 0.8.1: added "415. Add Strings"

Author: fartem

README.md

@@ -93,3 +93,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 409. Longest Palindrome                                | [Link](https://leetcode.com/problems/longest-palindrome/)                                 | [Link](./lib/easy/409_longest_palindrome.rb)                                |
 | 412. Fizz Buzz                                         | [Link](https://leetcode.com/problems/fizz-buzz/)                                          | [Link](./lib/easy/412_fizz_buzz.rb)                                         |
 | 414. Third Maximum Number                              | [Link](https://leetcode.com/problems/third-maximum-number/)                               | [Link](./lib/easy/414_third_maximum_number.rb)                              |
+| 415. Add Strings                                       | [Link](https://leetcode.com/problems/add-strings/)                                        | [Link](./lib/easy/415_add_strings.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 = '0.8.0'
+  s.version = '0.8.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[bin/leetcode-ruby README.md LICENSE]
   s.executable = 'leetcode-ruby'

lib/easy/415_add_strings.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/add-strings/
+# @param {String} num1
+# @param {String} num2
+# @return {String}
+def add_strings(num1, num2)
+  result = ''
+  num1_p = num1.length - 1
+  num2_p = num2.length - 1
+  addition = 0
+  while num1_p >= 0 || num2_p >= 0
+    first = next_num(num1, num1_p)
+    second = next_num(num2, num2_p)
+    sum = first + second
+    if addition == 1
+      sum += addition
+      addition = 0
+    end
+    if sum >= 10
+      sum -= 10
+      addition = 1
+    end
+    result += sum.to_s
+    num1_p -= 1
+    num2_p -= 1
+  end
+  result += addition.to_s if addition == 1
+
+  result.reverse
+end
+
+# @param {String} num
+# @param {Integer} index
+# @return {Integer}
+def next_num(num, index)
+  index >= 0 ? num[index].to_i(10) : 0
+end

test/easy/test_415_add_strings.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/easy/415_add_strings'
+require 'minitest/autorun'
+
+class AddStringsTest < ::Minitest::Test
+  def test_default
+    assert_equal('134', add_strings('11', '123'))
+    assert_equal('533', add_strings('456', '77'))
+    assert_equal('0', add_strings('0', '0'))
+  end
+end