Re-translate the Japanese version (#1871)

* Retranslate Japanese docs with GPT-5.4

* Retranslate Japanese code with GPT-5.4

ja/codes/ruby/chapter_searching/two_sum.rb

@@ -0,0 +1,46 @@
+=begin
+File: two_sum.rb
+Created Time: 2024-04-09
+Author: Blue Bean (lonnnnnnner@gmail.com)
+=end
+
+### 方法1：総当たり列挙 ###
+def two_sum_brute_force(nums, target)
+  # 2重ループのため、時間計算量は O(n^2)
+  for i in 0...(nums.length - 1)
+    for j in (i + 1)...nums.length
+      return [i, j] if nums[i] + nums[j] == target
+    end
+  end
+
+  []
+end
+
+### 方法2：補助ハッシュテーブル ###
+def two_sum_hash_table(nums, target)
+  # 補助ハッシュテーブルを使用し、空間計算量は O(n)
+  dic = {}
+  # 単一ループで、時間計算量は O(n)
+  for i in 0...nums.length
+    return [dic[target - nums[i]], i] if dic.has_key?(target - nums[i])
+
+    dic[nums[i]] = i
+  end
+
+  []
+end
+
+### Driver Code ###
+if __FILE__ == $0
+  # ======= Test Case =======
+  nums = [2, 7, 11, 15]
+  target = 13
+
+  # ====== Driver Code ======
+  # 方法 1
+  res = two_sum_brute_force(nums, target)
+  puts "方法1 res = #{res}"
+  # 方法 2
+  res = two_sum_hash_table(nums, target)
+  puts "方法2 res = #{res}"
+end