add missing header file <cstring> for exercise 22

DongDongBan · DongDongBan · commit 86ab037dc7ea · 2025-01-15T21:22:05.000+08:00
diff --git a/exercises/22_class_template/main.cpp b/exercises/22_class_template/main.cpp
@@ -1,5 +1,5 @@
 ﻿#include "../exercise.h"
-
+#include <cstring>
 // READ: 类模板 <https://zh.cppreference.com/w/cpp/language/class_template>
 
 template<class T>
