Re-translate the Japanese version (#1871)

* Retranslate Japanese docs with GPT-5.4

* Retranslate Japanese code with GPT-5.4

ja/codes/swift/utils/Pair.swift

@@ -0,0 +1,20 @@
+/**
+ * File: Pair.swift
+ * Created Time: 2023-06-28
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+/* キーと値の組 */
+public class Pair: Equatable {
+    public var key: Int
+    public var val: String
+
+    public init(key: Int, val: String) {
+        self.key = key
+        self.val = val
+    }
+
+    public static func == (lhs: Pair, rhs: Pair) -> Bool {
+        lhs.key == rhs.key && lhs.val == rhs.val
+    }
+}