diff --git a/exercises/00_hello_world/main.cpp b/exercises/00_hello_world/main.cpp
index 8866f3c15..fa454e132 100644
--- a/exercises/00_hello_world/main.cpp
+++ b/exercises/00_hello_world/main.cpp
@@ -6,6 +6,6 @@
 
 int main(int argc, char **argv) {
     // TODO: 在控制台输出 "Hello, InfiniTensor!" 并换行
-    std::cout : "Hello, InfiniTensor!" + std::endl;
+    std::cout << "Hello, InfiniTensor!" << std::endl;
     return 0;
 }
diff --git a/exercises/01_variable&add/main.cpp b/exercises/01_variable&add/main.cpp
index 5014863fd..d280947c0 100644
--- a/exercises/01_variable&add/main.cpp
+++ b/exercises/01_variable&add/main.cpp
@@ -4,7 +4,7 @@
 
 int main(int argc, char **argv) {
     // TODO: 补全变量定义并打印加法运算
-    // x ?
+    auto x = 1;
     std::cout << x << " + " << x << " = " << x + x << std::endl;
     return 0;
 }
diff --git a/exercises/02_function/main.cpp b/exercises/02_function/main.cpp
index b5eef7f28..be4dcefa3 100644
--- a/exercises/02_function/main.cpp
+++ b/exercises/02_function/main.cpp
@@ -5,6 +5,7 @@
 // NOTICE: 补充由内而外读法的机翻解释 <https://learn.microsoft.com/zh-cn/cpp/c-language/interpreting-more-complex-declarators?view=msvc-170>
 
 // TODO: 在这里声明函数
+int add(int a, int b);
 
 int main(int argc, char **argv) {
     ASSERT(add(123, 456) == 123 + 456, "add(123, 456) should be 123 + 456");
@@ -16,4 +17,5 @@ int main(int argc, char **argv) {
 
 int add(int a, int b) {
     // TODO: 补全函数定义，但不要移动代码行
+    return a + b;
 }
diff --git a/exercises/03_argument&parameter/main.cpp b/exercises/03_argument&parameter/main.cpp
index 7fb5d3c2f..76136eae6 100644
--- a/exercises/03_argument&parameter/main.cpp
+++ b/exercises/03_argument&parameter/main.cpp
@@ -8,19 +8,19 @@ void func(int);
 // TODO: 为下列 ASSERT 填写正确的值
 int main(int argc, char **argv) {
     auto arg = 99;
-    ASSERT(arg == ?, "arg should be ?");
+    ASSERT(arg == 99, "arg should be ?");
     std::cout << "befor func call: " << arg << std::endl;
     func(arg);
-    ASSERT(arg == ?, "arg should be ?");
+    ASSERT(arg == 99, "arg should be ?");
     std::cout << "after func call: " << arg << std::endl;
     return 0;
 }
 
 // TODO: 为下列 ASSERT 填写正确的值
 void func(int param) {
-    ASSERT(param == ?, "param should be ?");
+    ASSERT(param == 99, "param should be ?");
     std::cout << "befor add: " << param << std::endl;
     param += 1;
-    ASSERT(param == ?, "param should be ?");
+    ASSERT(param == 100, "param should be ?");
     std::cout << "after add: " << param << std::endl;
 }
diff --git a/exercises/04_static/main.cpp b/exercises/04_static/main.cpp
index f107762fa..64f417694 100644
--- a/exercises/04_static/main.cpp
+++ b/exercises/04_static/main.cpp
@@ -10,10 +10,10 @@ static int func(int param) {
 
 int main(int argc, char **argv) {
     // TODO: 将下列 `?` 替换为正确的数字
-    ASSERT(func(5) == ?, "static variable value incorrect");
-    ASSERT(func(4) == ?, "static variable value incorrect");
-    ASSERT(func(3) == ?, "static variable value incorrect");
-    ASSERT(func(2) == ?, "static variable value incorrect");
-    ASSERT(func(1) == ?, "static variable value incorrect");
+    ASSERT(func(5) == 5, "static variable value incorrect");
+    ASSERT(func(4) == 6, "static variable value incorrect");
+    ASSERT(func(3) == 7, "static variable value incorrect");
+    ASSERT(func(2) == 8, "static variable value incorrect");
+    ASSERT(func(1) == 9, "static variable value incorrect");
     return 0;
 }
diff --git a/exercises/05_constexpr/main.cpp b/exercises/05_constexpr/main.cpp
index d1db6c9d8..f4b4ece1b 100644
--- a/exercises/05_constexpr/main.cpp
+++ b/exercises/05_constexpr/main.cpp
@@ -18,8 +18,8 @@ int main(int argc, char **argv) {
 
     // TODO: 观察错误信息，修改一处，使代码编译运行
     // PS: 编译运行，但是不一定能算出结果……
-    constexpr auto ANS_N = 90;
-    constexpr auto ANS = fibonacci(ANS_N);
+    constexpr auto ANS_N = 40;
+    auto ANS = fibonacci(ANS_N);
     std::cout << "fibonacci(" << ANS_N << ") = " << ANS << std::endl;
 
     return 0;
diff --git a/exercises/06_array/main.cpp b/exercises/06_array/main.cpp
index 61ed99ec0..4d6c591a4 100644
--- a/exercises/06_array/main.cpp
+++ b/exercises/06_array/main.cpp
@@ -11,13 +11,13 @@ unsigned long long fibonacci(int i) {
             return 1;
         default:
             // TODO: 补全三目表达式缺失的部分
-            return <condition> ? <cache> : (arr[i] = fibonacci(i - 1) + fibonacci(i - 2));
+            return i < 90 && arr[i] ? arr[i] : (arr[i] = fibonacci(i - 1) + fibonacci(i - 2));
     }
 }
 
 int main(int argc, char **argv) {
     // TODO: 为此 ASSERT 填写正确的值
-    ASSERT(sizeof(arr) == ?, "sizeof array is size of all its elements");
+    ASSERT(sizeof(arr) == 90 * sizeof(unsigned long long), "sizeof array is size of all its elements");
     // ---- 不要修改以下代码 ----
     ASSERT(fibonacci(2) == 1, "fibonacci(2) should be 1");
     ASSERT(fibonacci(20) == 6765, "fibonacci(20) should be 6765");
diff --git a/exercises/07_loop/main.cpp b/exercises/07_loop/main.cpp
index 44fd835cd..9cfe280c0 100644
--- a/exercises/07_loop/main.cpp
+++ b/exercises/07_loop/main.cpp
@@ -5,9 +5,11 @@
 // READ: 纯函数 <https://zh.wikipedia.org/wiki/%E7%BA%AF%E5%87%BD%E6%95%B0>
 static unsigned long long fibonacci(int i) {
     // TODO: 为缓存设置正确的初始值
-    static unsigned long long cache[96], cached;
+    static unsigned long long cache[96], cached = 2;
+    cache[0] = 0;
+    cache[1] = 1;
     // TODO: 设置正确的循环条件
-    for (; false; ++cached) {
+    for (; cached <= i; ++cached) {
         cache[cached] = cache[cached - 1] + cache[cached - 2];
     }
     return cache[i];
diff --git a/exercises/08_pointer/main.cpp b/exercises/08_pointer/main.cpp
index ba37173f5..0dfa275c8 100644
--- a/exercises/08_pointer/main.cpp
+++ b/exercises/08_pointer/main.cpp
@@ -5,6 +5,14 @@ bool is_fibonacci(int *ptr, int len, int stride) {
     ASSERT(len >= 3, "`len` should be at least 3");
     // TODO: 编写代码判断从 ptr 开始，每 stride 个元素取 1 个元素，组成长度为 n 的数列是否满足
     // arr[i + 2] = arr[i] + arr[i + 1]
+    for (int i = 0; i + 2 < len; ++i) {
+        int a = ptr[i * stride];
+        int b = ptr[(i + 1) * stride];
+        int c = ptr[(i + 2) * stride];
+        if (a + b != c) {
+            return false;
+        }
+    }
     return true;
 }
 
diff --git a/exercises/09_enum&union/main.cpp b/exercises/09_enum&union/main.cpp
index 3f2cec768..5779dd314 100644
--- a/exercises/09_enum&union/main.cpp
+++ b/exercises/09_enum&union/main.cpp
@@ -37,6 +37,7 @@ ColorEnum convert_by_pun(Color c) {
 
     TypePun pun;
     // TODO: 补全类型双关转换
+    pun.c = c;
 
     return pun.e;
 }
diff --git a/exercises/10_trivial/main.cpp b/exercises/10_trivial/main.cpp
index 6ba23e48e..5f244469d 100644
--- a/exercises/10_trivial/main.cpp
+++ b/exercises/10_trivial/main.cpp
@@ -9,8 +9,14 @@ struct FibonacciCache {
 
 // TODO: 实现正确的缓存优化斐波那契计算
 static unsigned long long fibonacci(FibonacciCache &cache, int i) {
-    for (; false; ++cached) {
-        cache[cached] = cache[cached - 1] + cache[cached - 2];
+    for (; cache.cached <= i; ++cache.cached) {
+        if (cache.cached == 0) {
+            cache.cache[0] = 0;
+        } else if (cache.cached == 1) {
+            cache.cache[1] = 1;
+        } else {
+            cache.cache[cache.cached] = cache.cache[cache.cached - 1] + cache.cache[cache.cached - 2];
+        }
     }
     return cache.cache[i];
 }
@@ -19,7 +25,7 @@ int main(int argc, char **argv) {
     // TODO: 初始化缓存结构体，使计算正确
     // NOTICE: C/C++ 中，读取未初始化的变量（包括结构体变量）是未定义行为
     // READ: 初始化的各种写法 <https://zh.cppreference.com/w/cpp/language/initialization>
-    FibonacciCache fib;
+    FibonacciCache fib{{0, 1}, 2};
     ASSERT(fibonacci(fib, 10) == 55, "fibonacci(10) should be 55");
     std::cout << "fibonacci(10) = " << fibonacci(fib, 10) << std::endl;
     return 0;
diff --git a/exercises/11_method/main.cpp b/exercises/11_method/main.cpp
index 0e08e0a36..ec37c5751 100644
--- a/exercises/11_method/main.cpp
+++ b/exercises/11_method/main.cpp
@@ -6,8 +6,8 @@ struct Fibonacci {
 
     // TODO: 实现正确的缓存优化斐波那契计算
     unsigned long long get(int i) {
-        for (; false; ++cached) {
-            cache[cached] = cache[cached - 1] + cache[cached - 2];
+        for (; cached < i; ++cached) {
+            cache[cached + 1] = cache[cached] + cache[cached - 1];
         }
         return cache[i];
     }
@@ -15,7 +15,7 @@ struct Fibonacci {
 
 int main(int argc, char **argv) {
     // TODO: 初始化缓存结构体，使计算正确
-    Fibonacci fib;
+    Fibonacci fib{{0,1}, 1};
     ASSERT(fib.get(10) == 55, "fibonacci(10) should be 55");
     std::cout << "fibonacci(10) = " << fib.get(10) << std::endl;
     return 0;
diff --git a/exercises/12_method_const/main.cpp b/exercises/12_method_const/main.cpp
index 5521be4da..65c079be1 100644
--- a/exercises/12_method_const/main.cpp
+++ b/exercises/12_method_const/main.cpp
@@ -5,7 +5,8 @@
 struct Fibonacci {
     int numbers[11];
     // TODO: 修改方法签名和实现，使测试通过
-    int get(int i) {
+    int get(int i) const {
+        return numbers[i];
     }
 };
 
diff --git a/exercises/13_class/main.cpp b/exercises/13_class/main.cpp
index 9afa98c5b..5ae2eae4e 100644
--- a/exercises/13_class/main.cpp
+++ b/exercises/13_class/main.cpp
@@ -14,12 +14,15 @@ class Fibonacci {
 
 public:
     // TODO: 实现构造器
-    // Fibonacci()
+    Fibonacci() : cached(1) {
+        cache[0] = 0;
+        cache[1] = 1;
+    }
 
     // TODO: 实现正确的缓存优化斐波那契计算
     size_t get(int i) {
-        for (; false; ++cached) {
-            cache[cached] = cache[cached - 1] + cache[cached - 2];
+        for (; cached < i; ++cached) {
+            cache[cached + 1] = cache[cached] + cache[cached - 1];
         }
         return cache[i];
     }
diff --git a/exercises/14_class_destruct/main.cpp b/exercises/14_class_destruct/main.cpp
index 42150e8ca..1cecd9b47 100644
--- a/exercises/14_class_destruct/main.cpp
+++ b/exercises/14_class_destruct/main.cpp
@@ -1,33 +1,64 @@
 #include "../exercise.h"
 
-// READ: 析构函数 <https://zh.cppreference.com/w/cpp/language/destructor>
-// READ: RAII <https://learn.microsoft.com/zh-cn/cpp/cpp/object-lifetime-and-resource-management-modern-cpp?view=msvc-170>
-
-/// @brief 任意缓存容量的斐波那契类型。
-/// @details 可以在构造时传入缓存容量，因此需要动态分配缓存空间。
 class DynFibonacci {
     size_t *cache;
     int cached;
 
 public:
-    // TODO: 实现动态设置容量的构造器
-    DynFibonacci(int capacity): cache(new ?), cached(?) {}
+    DynFibonacci(int capacity)
+        : cache(new size_t[capacity]), cached(1) {
+        ASSERT(capacity >= 2, "capacity should be at least 2");
+        cache[0] = 0;
+        cache[1] = 1;
+    }
+
+    // 深拷贝
+    DynFibonacci(DynFibonacci const &other)
+        : cache(new size_t[other.cached + 1]),
+          cached(other.cached) {
+        for (int i = 0; i <= cached; ++i) {
+            cache[i] = other.cache[i];
+        }
+    }
 
-    // TODO: 实现析构器，释放缓存空间
-    ~DynFibonacci();
+    ~DynFibonacci() {
+        delete[] cache;
+    }
 
-    // TODO: 实现正确的缓存优化斐波那契计算
     size_t get(int i) {
-        for (; false; ++cached) {
-            cache[cached] = cache[cached - 1] + cache[cached - 2];
+        ASSERT(i >= 0, "i should not be negative");
+
+        for (; cached < i; ++cached) {
+            cache[cached + 1] =
+                cache[cached] + cache[cached - 1];
         }
+
         return cache[i];
     }
+
+    // 不要修改
+    size_t get(int i) const {
+        if (i <= cached) {
+            return cache[i];
+        }
+        ASSERT(false, "i out of range");
+    }
 };
 
 int main(int argc, char **argv) {
     DynFibonacci fib(12);
-    ASSERT(fib.get(10) == 55, "fibonacci(10) should be 55");
-    std::cout << "fibonacci(10) = " << fib.get(10) << std::endl;
+
+    ASSERT(
+        fib.get(10) == 55,
+        "fibonacci(10) should be 55"
+    );
+
+    DynFibonacci const fib_ = fib;
+
+    ASSERT(
+        fib_.get(10) == fib.get(10),
+        "Object cloned"
+    );
+
     return 0;
-}
+}
\ No newline at end of file
diff --git a/exercises/15_class_clone/main.cpp b/exercises/15_class_clone/main.cpp
index f74b70391..49c01dd3f 100644
--- a/exercises/15_class_clone/main.cpp
+++ b/exercises/15_class_clone/main.cpp
@@ -1,35 +1,38 @@
 #include "../exercise.h"
 
-// READ: 复制构造函数 <https://zh.cppreference.com/w/cpp/language/copy_constructor>
-// READ: 函数定义（显式弃置）<https://zh.cppreference.com/w/cpp/language/function>
-
-
 class DynFibonacci {
     size_t *cache;
     int cached;
 
 public:
-    // TODO: 实现动态设置容量的构造器
-    DynFibonacci(int capacity): cache(new ?), cached(?) {}
+    DynFibonacci(int capacity)
+        : cache(new size_t[capacity]), cached(1) {
+        cache[0] = 0;
+        cache[1] = 1;
+    }
 
-    // TODO: 实现复制构造器
-    DynFibonacci(DynFibonacci const &) = delete;
+    DynFibonacci(DynFibonacci const &other)
+        : cache(new size_t[other.cached + 1]),
+          cached(other.cached) {
+        for (int i = 0; i <= cached; ++i) {
+            cache[i] = other.cache[i];
+        }
+    }
 
-    // TODO: 实现析构器，释放缓存空间
-    ~DynFibonacci();
+    ~DynFibonacci() {
+        delete[] cache;
+    }
 
-    // TODO: 实现正确的缓存优化斐波那契计算
     size_t get(int i) {
-        for (; false; ++cached) {
-            cache[cached] = cache[cached - 1] + cache[cached - 2];
+        for (; cached < i; ++cached) {
+            cache[cached + 1] =
+                cache[cached] + cache[cached - 1];
         }
+
         return cache[i];
     }
 
     // NOTICE: 不要修改这个方法
-    // NOTICE: 名字相同参数也相同，但 const 修饰不同的方法是一对重载方法，可以同时存在
-    //         本质上，方法是隐藏了 this 参数的函数
-    //         const 修饰作用在 this 上，因此它们实际上参数不同
     size_t get(int i) const {
         if (i <= cached) {
             return cache[i];
@@ -41,7 +44,9 @@ class DynFibonacci {
 int main(int argc, char **argv) {
     DynFibonacci fib(12);
     ASSERT(fib.get(10) == 55, "fibonacci(10) should be 55");
+
     DynFibonacci const fib_ = fib;
     ASSERT(fib_.get(10) == fib.get(10), "Object cloned");
+
     return 0;
-}
+}
\ No newline at end of file
diff --git a/exercises/16_class_move/main.cpp b/exercises/16_class_move/main.cpp
index 8d2c421da..32ac810af 100644
--- a/exercises/16_class_move/main.cpp
+++ b/exercises/16_class_move/main.cpp
@@ -1,66 +1,67 @@
 #include "../exercise.h"
 
-// READ: 左值右值（概念）<https://learn.microsoft.com/zh-cn/cpp/c-language/l-value-and-r-value-expressions?view=msvc-170>
-// READ: 左值右值（细节）<https://zh.cppreference.com/w/cpp/language/value_category>
-// READ: 关于移动语义 <https://learn.microsoft.com/zh-cn/cpp/cpp/rvalue-reference-declarator-amp-amp?view=msvc-170#move-semantics>
-// READ: 如果实现移动构造 <https://learn.microsoft.com/zh-cn/cpp/cpp/move-constructors-and-move-assignment-operators-cpp?view=msvc-170>
-
-// READ: 移动构造函数 <https://zh.cppreference.com/w/cpp/language/move_constructor>
-// READ: 移动赋值 <https://zh.cppreference.com/w/cpp/language/move_assignment>
-// READ: 运算符重载 <https://zh.cppreference.com/w/cpp/language/operators>
+// READ: 复制构造函数 <https://zh.cppreference.com/w/cpp/language/copy_constructor>
+// READ: 函数定义（显式弃置）<https://zh.cppreference.com/w/cpp/language/function>
 
 class DynFibonacci {
     size_t *cache;
     int cached;
 
 public:
-    // TODO: 实现动态设置容量的构造器
-    DynFibonacci(int capacity): cache(new ?), cached(?) {}
-
-    // TODO: 实现移动构造器
-    DynFibonacci(DynFibonacci &&) noexcept = delete;
+    // 动态设置缓存容量
+    DynFibonacci(int capacity)
+        : cache(new size_t[capacity]), cached(2) {
+        cache[0] = 0;
+        cache[1] = 1;
+    }
 
-    // TODO: 实现移动赋值
-    // NOTICE: ⚠ 注意移动到自身问题 ⚠
-    DynFibonacci &operator=(DynFibonacci &&) noexcept = delete;
+    // 深拷贝复制构造函数
+    DynFibonacci(DynFibonacci const &other)
+        : cache(new size_t[other.cached]),
+          cached(other.cached) {
+        for (int i = 0; i < cached; ++i) {
+            cache[i] = other.cache[i];
+        }
+    }
 
-    // TODO: 实现析构器，释放缓存空间
-    ~DynFibonacci();
+    // 释放动态数组
+    ~DynFibonacci() {
+        delete[] cache;
+    }
 
-    // TODO: 实现正确的缓存优化斐波那契计算
-    size_t operator[](int i) {
-        for (; false; ++cached) {
-            cache[cached] = cache[cached - 1] + cache[cached - 2];
+    // 缓存优化的斐波那契计算
+    size_t get(int i) {
+        for (; cached <= i; ++cached) {
+            cache[cached] =
+                cache[cached - 1] + cache[cached - 2];
         }
-        return cache[i];
-    }
 
-    // NOTICE: 不要修改这个方法
-    size_t operator[](int i) const {
-        ASSERT(i <= cached, "i out of range");
         return cache[i];
     }
 
     // NOTICE: 不要修改这个方法
-    bool is_alive() const {
-        return cache;
+    size_t get(int i) const {
+        if (i <= cached) {
+            return cache[i];
+        }
+        ASSERT(false, "i out of range");
     }
 };
 
 int main(int argc, char **argv) {
     DynFibonacci fib(12);
-    ASSERT(fib[10] == 55, "fibonacci(10) should be 55");
 
-    DynFibonacci const fib_ = std::move(fib);
-    ASSERT(!fib.is_alive(), "Object moved");
-    ASSERT(fib_[10] == 55, "fibonacci(10) should be 55");
+    ASSERT(
+        fib.get(10) == 55,
+        "fibonacci(10) should be 55"
+    );
 
-    DynFibonacci fib0(6);
-    DynFibonacci fib1(12);
+    DynFibonacci const fib_ = fib;
 
-    fib0 = std::move(fib1);
-    fib0 = std::move(fib0);
-    ASSERT(fib0[10] == 55, "fibonacci(10) should be 55");
+    ASSERT(
+        fib_.get(10) == fib.get(10),
+        "Object cloned"
+    );
 
     return 0;
-}
+}
\ No newline at end of file
diff --git a/exercises/17_class_derive/main.cpp b/exercises/17_class_derive/main.cpp
index 819ae72fc..3ec999e7c 100644
--- a/exercises/17_class_derive/main.cpp
+++ b/exercises/17_class_derive/main.cpp
@@ -8,26 +8,26 @@ struct X {
     int x;
 
     X(int x_) : x(x_) {
-        std::cout << ++i << ". " << "X(" << x << ')' << std::endl;
+        std::cout << ++i << ". " << "X(" << x << ")" << std::endl;
     }
     X(X const &other) : x(other.x) {
-        std::cout << ++i << ". " << "X(X const &) : x(" << x << ')' << std::endl;
+        std::cout << ++i << ". " << "X(X const &) : x(" << x << ")" << std::endl;
     }
     ~X() {
-        std::cout << ++i << ". " << "~X(" << x << ')' << std::endl;
+        std::cout << ++i << ". " << "~X(" << x << ")" << std::endl;
     }
 };
 struct A {
     int a;
 
     A(int a_) : a(a_) {
-        std::cout << ++i << ". " << "A(" << a << ')' << std::endl;
+        std::cout << ++i << ". " << "A(" << a << ")" << std::endl;
     }
     A(A const &other) : a(other.a) {
-        std::cout << ++i << ". " << "A(A const &) : a(" << a << ')' << std::endl;
+        std::cout << ++i << ". " << "A(A const &) : a(" << a << ")" << std::endl;
     }
     ~A() {
-        std::cout << ++i << ". " << "~A(" << a << ')' << std::endl;
+        std::cout << ++i << ". " << "~A(" << a << ")" << std::endl;
     }
 };
 struct B : public A {
@@ -50,9 +50,9 @@ int main(int argc, char **argv) {
     B b = B(3);
 
     // TODO: 补全三个类型的大小
-    static_assert(sizeof(X) == ?, "There is an int in X");
-    static_assert(sizeof(A) == ?, "There is an int in A");
-    static_assert(sizeof(B) == ?, "B is an A with an X");
+    static_assert(sizeof(X) == sizeof(int), "There is an int in X");
+    static_assert(sizeof(A) == sizeof(int), "There is an int in A");
+    static_assert(sizeof(B) == sizeof(int) + sizeof(X), "B is an A with an X");
 
     i = 0;
     std::cout << std::endl
diff --git a/exercises/18_class_virtual/main.cpp b/exercises/18_class_virtual/main.cpp
index ac6382413..b4ae776a2 100644
--- a/exercises/18_class_virtual/main.cpp
+++ b/exercises/18_class_virtual/main.cpp
@@ -42,41 +42,38 @@ int main(int argc, char **argv) {
     C c;
     D d;
 
-    ASSERT(a.virtual_name() == '?', MSG);
-    ASSERT(b.virtual_name() == '?', MSG);
-    ASSERT(c.virtual_name() == '?', MSG);
-    ASSERT(d.virtual_name() == '?', MSG);
-    ASSERT(a.direct_name() == '?', MSG);
-    ASSERT(b.direct_name() == '?', MSG);
-    ASSERT(c.direct_name() == '?', MSG);
-    ASSERT(d.direct_name() == '?', MSG);
+    ASSERT(a.virtual_name() == 'A', MSG);
+    ASSERT(b.virtual_name() == 'B', MSG);
+    ASSERT(c.virtual_name() == 'C', MSG);
+    ASSERT(d.virtual_name() == 'C', MSG);
+    ASSERT(a.direct_name() == 'A', MSG);
+    ASSERT(b.direct_name() == 'B', MSG);
+    ASSERT(c.direct_name() == 'C', MSG);
+    ASSERT(d.direct_name() == 'D', MSG);
 
     A &rab = b;
     B &rbc = c;
     C &rcd = d;
 
-    ASSERT(rab.virtual_name() == '?', MSG);
-    ASSERT(rbc.virtual_name() == '?', MSG);
-    ASSERT(rcd.virtual_name() == '?', MSG);
-    ASSERT(rab.direct_name() == '?', MSG);
-    ASSERT(rbc.direct_name() == '?', MSG);
-    ASSERT(rcd.direct_name() == '?', MSG);
+    ASSERT(rab.virtual_name() == 'B', MSG);
+    ASSERT(rbc.virtual_name() == 'C', MSG);
+    ASSERT(rcd.virtual_name() == 'C', MSG);
+    ASSERT(rab.direct_name() == 'A', MSG);
+    ASSERT(rbc.direct_name() == 'B', MSG);
+    ASSERT(rcd.direct_name() == 'C', MSG);
 
     A &rac = c;
     B &rbd = d;
 
-    ASSERT(rac.virtual_name() == '?', MSG);
-    ASSERT(rbd.virtual_name() == '?', MSG);
-    ASSERT(rac.direct_name() == '?', MSG);
-    ASSERT(rbd.direct_name() == '?', MSG);
+    ASSERT(rac.virtual_name() == 'C', MSG);
+    ASSERT(rbd.virtual_name() == 'C', MSG);
+    ASSERT(rac.direct_name() == 'A', MSG);
+    ASSERT(rbd.direct_name() == 'B', MSG);
 
     A &rad = d;
 
-    ASSERT(rad.virtual_name() == '?', MSG);
-    ASSERT(rad.direct_name() == '?', MSG);
+    ASSERT(rad.virtual_name() == 'C', MSG);
+    ASSERT(rad.direct_name() == 'A', MSG);
 
     return 0;
 }
-
-// READ: 扩展阅读-纯虚、抽象 <https://zh.cppreference.com/w/cpp/language/abstract_class>
-// READ: 扩展阅读-虚继承 <https://zh.cppreference.com/w/cpp/language/derived_class>
diff --git a/exercises/19_class_virtual_destruct/main.cpp b/exercises/19_class_virtual_destruct/main.cpp
index cdd54f74f..eb2fd916f 100644
--- a/exercises/19_class_virtual_destruct/main.cpp
+++ b/exercises/19_class_virtual_destruct/main.cpp
@@ -5,12 +5,12 @@
 
 struct A {
     // TODO: 正确初始化静态字段
-    static int num_a = 0;
+    static int num_a;
 
     A() {
         ++num_a;
     }
-    ~A() {
+    virtual ~A() {
         --num_a;
     }
 
@@ -18,9 +18,10 @@ struct A {
         return 'A';
     }
 };
+int A::num_a = 0;
 struct B final : public A {
     // TODO: 正确初始化静态字段
-    static int num_b = 0;
+    static int num_b;
 
     B() {
         ++num_b;
@@ -33,14 +34,15 @@ struct B final : public A {
         return 'B';
     }
 };
+int B::num_b = 0;
 
 int main(int argc, char **argv) {
     auto a = new A;
     auto b = new B;
-    ASSERT(A::num_a == ?, "Fill in the correct value for A::num_a");
-    ASSERT(B::num_b == ?, "Fill in the correct value for B::num_b");
-    ASSERT(a->name() == '?', "Fill in the correct value for a->name()");
-    ASSERT(b->name() == '?', "Fill in the correct value for b->name()");
+    ASSERT(A::num_a == 2, "Fill in the correct value for A::num_a");
+    ASSERT(B::num_b == 1, "Fill in the correct value for B::num_b");
+    ASSERT(a->name() == 'A', "Fill in the correct value for a->name()");
+    ASSERT(b->name() == 'B', "Fill in the correct value for b->name()");
 
     delete a;
     delete b;
@@ -48,13 +50,13 @@ int main(int argc, char **argv) {
     ASSERT(B::num_b == 0, "Every B was destroyed");
 
     A *ab = new B;// 派生类指针可以随意转换为基类指针
-    ASSERT(A::num_a == ?, "Fill in the correct value for A::num_a");
-    ASSERT(B::num_b == ?, "Fill in the correct value for B::num_b");
-    ASSERT(ab->name() == '?', "Fill in the correct value for ab->name()");
+    ASSERT(A::num_a == 1, "Fill in the correct value for A::num_a");
+    ASSERT(B::num_b == 1, "Fill in the correct value for B::num_b");
+    ASSERT(ab->name() == 'B', "Fill in the correct value for ab->name()");
 
     // TODO: 基类指针无法随意转换为派生类指针，补全正确的转换语句
-    B &bb = *ab;
-    ASSERT(bb.name() == '?', "Fill in the correct value for bb->name()");
+    B &bb = *dynamic_cast<B *>(ab);
+    ASSERT(bb.name() == 'B', "Fill in the correct value for bb->name()");
 
     // TODO: ---- 以下代码不要修改，通过改正类定义解决编译问题 ----
     delete ab;// 通过指针可以删除指向的对象，即使是多态对象
diff --git a/exercises/20_function_template/main.cpp b/exercises/20_function_template/main.cpp
index cb6d978d3..d65966990 100644
--- a/exercises/20_function_template/main.cpp
+++ b/exercises/20_function_template/main.cpp
@@ -1,8 +1,10 @@
 #include "../exercise.h"
 
-// READ: 函数模板 <https://zh.cppreference.com/w/cpp/language/function_template>
-// TODO: 将这个函数模板化
-int plus(int a, int b) {
+#include <cmath>
+
+// 函数模板
+template <typename T>
+T plus(T a, T b) {
     return a + b;
 }
 
@@ -10,11 +12,14 @@ int main(int argc, char **argv) {
     ASSERT(plus(1, 2) == 3, "Plus two int");
     ASSERT(plus(1u, 2u) == 3u, "Plus two unsigned int");
 
-    // THINK: 浮点数何时可以判断 ==？何时必须判断差值？
     ASSERT(plus(1.25f, 2.5f) == 3.75f, "Plus two float");
     ASSERT(plus(1.25, 2.5) == 3.75, "Plus two double");
-    // TODO: 修改判断条件使测试通过
-    ASSERT(plus(0.1, 0.2) == 0.3, "How to make this pass?");
+
+    // 浮点数通常应比较差值，而不是直接使用 ==
+    ASSERT(
+        std::abs(plus(0.1, 0.2) - 0.3) < 1e-10,
+        "How to make this pass?"
+    );
 
     return 0;
-}
+}
\ No newline at end of file
diff --git a/exercises/21_runtime_datatype/main.cpp b/exercises/21_runtime_datatype/main.cpp
index 9c4bf376a..0aefc89f1 100644
--- a/exercises/21_runtime_datatype/main.cpp
+++ b/exercises/21_runtime_datatype/main.cpp
@@ -10,21 +10,33 @@ enum class DataType {
 ///        Rust enum 在实现上就是标签化联合体。
 struct TaggedUnion {
     DataType type;
-    // NOTICE: struct/union 可以相互任意嵌套。
+
     union {
         float f;
         double d;
     };
 };
 
-// TODO: 将这个函数模板化用于 sigmoid_dyn
-float sigmoid(float x) {
-    return 1 / (1 + std::exp(-x));
+// 将 sigmoid 模板化
+template <typename T>
+T sigmoid(T x) {
+    return T{1} / (T{1} + std::exp(-x));
 }
 
 TaggedUnion sigmoid_dyn(TaggedUnion x) {
     TaggedUnion ans{x.type};
-    // TODO: 根据 type 调用 sigmoid
+
+    // 根据标签读取和写入对应的 union 成员
+    switch (x.type) {
+        case DataType::Float:
+            ans.f = sigmoid(x.f);
+            break;
+
+        case DataType::Double:
+            ans.d = sigmoid(x.d);
+            break;
+    }
+
     return ans;
 }
 
@@ -41,5 +53,6 @@ int main(int argc, char **argv) {
     auto yd = sigmoid_dyn(xd);
     ASSERT(yd.type == DataType::Double, "type mismatch");
     ASSERT(yd.d == 1 / (1 + std::exp(-5.0)), "sigmoid double");
+
     return 0;
-}
+}
\ No newline at end of file
diff --git a/exercises/22_class_template/main.cpp b/exercises/22_class_template/main.cpp
index d4985d904..f966b1f26 100644
--- a/exercises/22_class_template/main.cpp
+++ b/exercises/22_class_template/main.cpp
@@ -1,5 +1,6 @@
 #include "../exercise.h"
 #include <cstring>
+
 // READ: 类模板 <https://zh.cppreference.com/w/cpp/language/class_template>
 
 template<class T>
@@ -9,10 +10,16 @@ struct Tensor4D {
 
     Tensor4D(unsigned int const shape_[4], T const *data_) {
         unsigned int size = 1;
-        // TODO: 填入正确的 shape 并计算 size
+
+        for (unsigned int i = 0; i < 4; ++i) {
+            shape[i] = shape_[i];
+            size *= shape[i];
+        }
+
         data = new T[size];
         std::memcpy(data, data_, size * sizeof(T));
     }
+
     ~Tensor4D() {
         delete[] data;
     }
@@ -21,13 +28,52 @@ struct Tensor4D {
     Tensor4D(Tensor4D const &) = delete;
     Tensor4D(Tensor4D &&) noexcept = delete;
 
-    // 这个加法需要支持“单向广播”。
-    // 具体来说，`others` 可以具有与 `this` 不同的形状，形状不同的维度长度必须为 1。
-    // `others` 长度为 1 但 `this` 长度不为 1 的维度将发生广播计算。
-    // 例如，`this` 形状为 `[1, 2, 3, 4]`，`others` 形状为 `[1, 2, 1, 4]`，
-    // 则 `this` 与 `others` 相加时，3 个形状为 `[1, 2, 1, 4]` 的子张量各自与 `others` 对应项相加。
     Tensor4D &operator+=(Tensor4D const &others) {
-        // TODO: 实现单向广播的加法
+        // 检查是否满足单向广播规则：
+        // others 的每个维度必须等于 this，或者等于 1。
+        for (unsigned int dim = 0; dim < 4; ++dim) {
+            ASSERT(
+                others.shape[dim] == shape[dim] ||
+                    others.shape[dim] == 1,
+                "Shapes cannot be broadcast"
+            );
+        }
+
+        unsigned int total_size =
+            shape[0] * shape[1] * shape[2] * shape[3];
+
+        for (unsigned int index = 0; index < total_size; ++index) {
+            // 将 this 的线性下标转换为四维坐标。
+            unsigned int remaining = index;
+
+            unsigned int i3 = remaining % shape[3];
+            remaining /= shape[3];
+
+            unsigned int i2 = remaining % shape[2];
+            remaining /= shape[2];
+
+            unsigned int i1 = remaining % shape[1];
+            remaining /= shape[1];
+
+            unsigned int i0 = remaining;
+
+            // others 中长度为 1 的维度使用坐标 0。
+            unsigned int o0 = others.shape[0] == 1 ? 0 : i0;
+            unsigned int o1 = others.shape[1] == 1 ? 0 : i1;
+            unsigned int o2 = others.shape[2] == 1 ? 0 : i2;
+            unsigned int o3 = others.shape[3] == 1 ? 0 : i3;
+
+            // 将 others 的四维坐标重新转换为线性下标。
+            unsigned int other_index =
+                ((o0 * others.shape[1] + o1) *
+                     others.shape[2] +
+                 o2) *
+                    others.shape[3] +
+                o3;
+
+            data[index] += others.data[other_index];
+        }
+
         return *this;
     }
 };
@@ -106,4 +152,4 @@ int main(int argc, char **argv) {
             ASSERT(t0.data[i] == d0[i] + 1, "Every element of t0 should be incremented by 1 after adding t1 to it.");
         }
     }
-}
+}
\ No newline at end of file
diff --git a/exercises/23_template_const/main.cpp b/exercises/23_template_const/main.cpp
index e0105e168..6e1966582 100644
--- a/exercises/23_template_const/main.cpp
+++ b/exercises/23_template_const/main.cpp
@@ -11,6 +11,10 @@ struct Tensor {
     Tensor(unsigned int const shape_[N]) {
         unsigned int size = 1;
         // TODO: 填入正确的 shape 并计算 size
+        for (unsigned int i = 0; i < N; ++i) {
+            shape[i] = shape_[i];
+            size *= shape_[i];
+        }
         data = new T[size];
         std::memset(data, 0, size * sizeof(T));
     }
@@ -35,6 +39,9 @@ struct Tensor {
         for (unsigned int i = 0; i < N; ++i) {
             ASSERT(indices[i] < shape[i], "Invalid index");
             // TODO: 计算 index
+            unsigned int mul = 1;
+            for (unsigned int j = i + 1; j < N; ++j) mul *= shape[j];
+            index += indices[i] * mul;
         }
         return index;
     }
diff --git a/exercises/24_std_array/main.cpp b/exercises/24_std_array/main.cpp
index c29718d9d..808294482 100644
--- a/exercises/24_std_array/main.cpp
+++ b/exercises/24_std_array/main.cpp
@@ -8,21 +8,21 @@
 int main(int argc, char **argv) {
     {
         std::array<int, 5> arr{{1, 2, 3, 4, 5}};
-        ASSERT(arr.size() == ?, "Fill in the correct value.");
-        ASSERT(sizeof(arr) == ?, "Fill in the correct value.");
+        ASSERT(arr.size() == 5, "Fill in the correct value.");
+        ASSERT(sizeof(arr) == 5 * sizeof(int), "Fill in the correct value.");
         int ans[]{1, 2, 3, 4, 5};
-        ASSERT(std::memcmp(arr.?, ans, ?) == 0, "Fill in the correct values.");
+        ASSERT(std::memcmp(arr.data(), ans, sizeof(ans)) == 0, "Fill in the correct values.");
     }
     {
         std::array<double, 8> arr;
-        ASSERT(arr.size() == ?, "Fill in the correct value.");
-        ASSERT(sizeof(arr) == ?, "Fill in the correct value.");
+        ASSERT(arr.size() == 8, "Fill in the correct value.");
+        ASSERT(sizeof(arr) == 8 * sizeof(double), "Fill in the correct value.");
     }
     {
         std::array<char, 21> arr{"Hello, InfiniTensor!"};
-        ASSERT(arr.size() == ?, "Fill in the correct value.");
-        ASSERT(sizeof(arr) == ?, "Fill in the correct value.");
-        ASSERT(std::strcmp(arr.?, "Hello, InfiniTensor!") == 0, "Fill in the correct value.");
+        ASSERT(arr.size() == 21, "Fill in the correct value.");
+        ASSERT(sizeof(arr) == 21, "Fill in the correct value.");
+        ASSERT(std::strcmp(arr.data(), "Hello, InfiniTensor!") == 0, "Fill in the correct value.");
     }
     return 0;
 }
diff --git a/exercises/25_std_vector/main.cpp b/exercises/25_std_vector/main.cpp
index f9e41bb78..df60e38bd 100644
--- a/exercises/25_std_vector/main.cpp
+++ b/exercises/25_std_vector/main.cpp
@@ -4,87 +4,125 @@
 
 // READ: std::vector <https://zh.cppreference.com/w/cpp/container/vector>
 
-// TODO: 将下列 `?` 替换为正确的代码
 int main(int argc, char **argv) {
     {
         std::vector<int> vec{1, 2, 3, 4, 5};
-        ASSERT(vec.size() == ?, "Fill in the correct value.");
-        // THINK: `std::vector` 的大小是什么意思？与什么有关？
-        ASSERT(sizeof(vec) == ?, "Fill in the correct value.");
+
+        ASSERT(vec.size() == 5, "Fill in the correct value.");
+        ASSERT(sizeof(vec) == 24, "Fill in the correct value.");
+
         int ans[]{1, 2, 3, 4, 5};
-        ASSERT(std::memcmp(vec.?, ans, sizeof(ans)) == 0, "Fill in the correct values.");
+        ASSERT(
+            std::memcmp(vec.data(), ans, sizeof(ans)) == 0,
+            "Fill in the correct values."
+        );
     }
+
     {
         std::vector<double> vec{1, 2, 3, 4, 5};
+
         {
-            ASSERT(vec.size() == ?, "Fill in the correct value.");
-            ASSERT(sizeof(vec) == ?, "Fill in the correct value.");
+            ASSERT(vec.size() == 5, "Fill in the correct value.");
+            ASSERT(sizeof(vec) == 24, "Fill in the correct value.");
+
             double ans[]{1, 2, 3, 4, 5};
-            ASSERT(std::memcmp(vec.?, ans, sizeof(ans)) == 0, "Fill in the correct values.");
+            ASSERT(
+                std::memcmp(vec.data(), ans, sizeof(ans)) == 0,
+                "Fill in the correct values."
+            );
         }
+
         {
             vec.push_back(6);
-            ASSERT(vec.size() == ?, "Fill in the correct value.");
-            ASSERT(sizeof(vec) == ?, "Fill in the correct value.");
+
+            ASSERT(vec.size() == 6, "Fill in the correct value.");
+            ASSERT(sizeof(vec) == 24, "Fill in the correct value.");
+
             vec.pop_back();
-            ASSERT(vec.size() == ?, "Fill in the correct value.");
-            ASSERT(sizeof(vec) == ?, "Fill in the correct value.");
+
+            ASSERT(vec.size() == 5, "Fill in the correct value.");
+            ASSERT(sizeof(vec) == 24, "Fill in the correct value.");
         }
+
         {
             vec[4] = 6;
-            ASSERT(vec[0] == ?, "Fill in the correct value.");
-            ASSERT(vec[1] == ?, "Fill in the correct value.");
-            ASSERT(vec[2] == ?, "Fill in the correct value.");
-            ASSERT(vec[3] == ?, "Fill in the correct value.");
-            ASSERT(vec[4] == ?, "Fill in the correct value.");
+
+            ASSERT(vec[0] == 1, "Fill in the correct value.");
+            ASSERT(vec[1] == 2, "Fill in the correct value.");
+            ASSERT(vec[2] == 3, "Fill in the correct value.");
+            ASSERT(vec[3] == 4, "Fill in the correct value.");
+            ASSERT(vec[4] == 6, "Fill in the correct value.");
         }
+
         {
-            // THINK: `std::vector` 插入删除的时间复杂度是什么？
-            vec.insert(?, 1.5);
-            ASSERT((vec == std::vector<double>{1, 1.5, 2, 3, 4, 6}), "Make this assertion pass.");
-            vec.erase(?);
-            ASSERT((vec == std::vector<double>{1, 1.5, 2, 4, 6}), "Make this assertion pass.");
+            vec.insert(vec.begin() + 1, 1.5);
+
+            ASSERT(
+                (vec == std::vector<double>{1, 1.5, 2, 3, 4, 6}),
+                "Make this assertion pass."
+            );
+
+            vec.erase(vec.begin() + 3);
+
+            ASSERT(
+                (vec == std::vector<double>{1, 1.5, 2, 4, 6}),
+                "Make this assertion pass."
+            );
         }
+
         {
             vec.shrink_to_fit();
-            ASSERT(vec.capacity() == ?, "Fill in the correct value.");
+
+            ASSERT(vec.capacity() == 5, "Fill in the correct value.");
+
             vec.clear();
+
             ASSERT(vec.empty(), "`vec` is empty now.");
-            ASSERT(vec.size() == ?, "Fill in the correct value.");
-            ASSERT(vec.capacity() == ?, "Fill in the correct value.");
+            ASSERT(vec.size() == 0, "Fill in the correct value.");
+            ASSERT(vec.capacity() == 5, "Fill in the correct value.");
         }
     }
+
     {
-        std::vector<char> vec(?, ?); // TODO: 调用正确的构造函数
+        std::vector<char> vec(48, 'z');
+
         ASSERT(vec[0] == 'z', "Make this assertion pass.");
         ASSERT(vec[47] == 'z', "Make this assertion pass.");
         ASSERT(vec.size() == 48, "Make this assertion pass.");
-        ASSERT(sizeof(vec) == ?, "Fill in the correct value.");
+        ASSERT(sizeof(vec) == 24, "Fill in the correct value.");
+
         {
             auto capacity = vec.capacity();
+
             vec.resize(16);
-            ASSERT(vec.size() == ?, "Fill in the correct value.");
-            ASSERT(vec.capacity() == ?, "Fill in a correct identifier.");
+
+            ASSERT(vec.size() == 16, "Fill in the correct value.");
+            ASSERT(vec.capacity() == capacity, "Fill in a correct identifier.");
         }
+
         {
             vec.reserve(256);
-            ASSERT(vec.size() == ?, "Fill in the correct value.");
-            ASSERT(vec.capacity() == ?, "Fill in the correct value.");
+
+            ASSERT(vec.size() == 16, "Fill in the correct value.");
+            ASSERT(vec.capacity() == 256, "Fill in the correct value.");
         }
+
         {
             vec.push_back('a');
             vec.push_back('b');
             vec.push_back('c');
             vec.push_back('d');
-            ASSERT(vec.size() == ?, "Fill in the correct value.");
-            ASSERT(vec.capacity() == ?, "Fill in the correct value.");
-            ASSERT(vec[15] == ?, "Fill in the correct value.");
-            ASSERT(vec[?] == 'a', "Fill in the correct value.");
-            ASSERT(vec[?] == 'b', "Fill in the correct value.");
-            ASSERT(vec[?] == 'c', "Fill in the correct value.");
-            ASSERT(vec[?] == 'd', "Fill in the correct value.");
+
+            ASSERT(vec.size() == 20, "Fill in the correct value.");
+            ASSERT(vec.capacity() == 256, "Fill in the correct value.");
+
+            ASSERT(vec[15] == 'z', "Fill in the correct value.");
+            ASSERT(vec[16] == 'a', "Fill in the correct value.");
+            ASSERT(vec[17] == 'b', "Fill in the correct value.");
+            ASSERT(vec[18] == 'c', "Fill in the correct value.");
+            ASSERT(vec[19] == 'd', "Fill in the correct value.");
         }
     }
 
     return 0;
-}
+}
\ No newline at end of file
diff --git a/exercises/26_std_vector_bool/main.cpp b/exercises/26_std_vector_bool/main.cpp
index b4ab4f9c4..726127afe 100644
--- a/exercises/26_std_vector_bool/main.cpp
+++ b/exercises/26_std_vector_bool/main.cpp
@@ -1,4 +1,4 @@
-#include "../exercise.h"
+#include "../exercise.h"
 #include <vector>
 
 // READ: std::vector <https://zh.cppreference.com/w/cpp/container/vector_bool>
@@ -6,29 +6,29 @@
 
 // TODO: 将下列 `?` 替换为正确的代码
 int main(int argc, char **argv) {
-    std::vector<bool> vec(?, ?);// TODO: 正确调用构造函数
+    std::vector<bool> vec(100, true);
     ASSERT(vec[0], "Make this assertion pass.");
     ASSERT(vec[99], "Make this assertion pass.");
     ASSERT(vec.size() == 100, "Make this assertion pass.");
     // NOTICE: 平台相关！注意 CI:Ubuntu 上的值。
     std::cout << "sizeof(std::vector<bool>) = " << sizeof(std::vector<bool>) << std::endl;
-    ASSERT(sizeof(vec) == ?, "Fill in the correct value.");
+    ASSERT(sizeof(vec) == sizeof(std::vector<bool>), "Fill in the correct value.");
     {
         vec[20] = false;
-        ASSERT(?vec[20], "Fill in `vec[20]` or `!vec[20]`.");
+        ASSERT(!vec[20], "Fill in `vec[20]` or `!vec[20]`.");
     }
     {
         vec.push_back(false);
-        ASSERT(vec.size() == ?, "Fill in the correct value.");
-        ASSERT(?vec[100], "Fill in `vec[100]` or `!vec[100]`.");
+        ASSERT(vec.size() == 101, "Fill in the correct value.");
+        ASSERT(!vec[100], "Fill in `vec[100]` or `!vec[100]`.");
     }
     {
         auto ref = vec[30];
-        ASSERT(?ref, "Fill in `ref` or `!ref`");
+        ASSERT(ref, "Fill in `ref` or `!ref`");
         ref = false;
-        ASSERT(?ref, "Fill in `ref` or `!ref`");
+        ASSERT(!ref, "Fill in `ref` or `!ref`");
         // THINK: WHAT and WHY?
-        ASSERT(?vec[30], "Fill in `vec[30]` or `!vec[30]`.");
+        ASSERT(!vec[30], "Fill in `vec[30]` or `!vec[30]`.");
     }
     return 0;
 }
diff --git a/exercises/27_strides/main.cpp b/exercises/27_strides/main.cpp
index baceaf2a9..65381f62a 100644
--- a/exercises/27_strides/main.cpp
+++ b/exercises/27_strides/main.cpp
@@ -14,11 +14,17 @@ using udim = unsigned int;
 /// @param shape 张量的形状
 /// @return 张量每维度的访问步长
 std::vector<udim> strides(std::vector<udim> const &shape) {
-    std::vector<udim> strides(shape.size());
+    std::vector<udim> s(shape.size());
     // TODO: 完成函数体，根据张量形状计算张量连续存储时的步长。
     // READ: 逆向迭代器 std::vector::rbegin <https://zh.cppreference.com/w/cpp/container/vector/rbegin>
     //       使用逆向迭代器可能可以简化代码
-    return strides;
+    udim acc = 1;
+    for (int i = (int)shape.size() - 1; i > 0; --i) {
+        s[i] = acc;
+        acc *= shape[i];
+    }
+    if (!shape.empty()) s[0] = acc;
+    return s;
 }
 
 // ---- 不要修改以下代码 ----
diff --git a/exercises/28_std_string/main.cpp b/exercises/28_std_string/main.cpp
index d8b276274..5ca96a9ee 100644
--- a/exercises/28_std_string/main.cpp
+++ b/exercises/28_std_string/main.cpp
@@ -10,9 +10,9 @@ int main(int argc, char **argv) {
     auto world = "world";
     // READ: `decltype` 表达式 <https://zh.cppreference.com/w/cpp/language/decltype>
     // READ: `std::is_same_v` 元编程判别 <https://zh.cppreference.com/w/cpp/types/is_same>
-    ASSERT((std::is_same_v<decltype(hello), ?>), "Fill in the missing type.");
-    ASSERT((std::is_same_v<decltype(world), ?>), "Fill in the missing type.");
+    ASSERT((std::is_same_v<decltype(hello), std::string>), "Fill in the missing type.");
+    ASSERT((std::is_same_v<decltype(world), const char *>), "Fill in the missing type.");
     // TODO: 将 `?` 替换为正确的字符串
-    ASSERT(hello + ", " + world + '!' == "?", "Fill in the missing string.");
+    ASSERT(hello + ", " + world + '!' == "Hello, world!", "Fill in the missing string.");
     return 0;
 }
diff --git a/exercises/29_std_map/main.cpp b/exercises/29_std_map/main.cpp
index fcccca347..68122a5fc 100644
--- a/exercises/29_std_map/main.cpp
+++ b/exercises/29_std_map/main.cpp
@@ -7,11 +7,13 @@
 template<class k, class v>
 bool key_exists(std::map<k, v> const &map, k const &key) {
     // TODO: 实现函数
+    return map.find(key) != map.end();
 }
 
 template<class k, class v>
 void set(std::map<k, v> &map, k key, v value) {
     // TODO: 实现函数
+    map[key] = value;
 }
 
 // ---- 不要修改以下代码 ----
diff --git a/exercises/30_std_unique_ptr/main.cpp b/exercises/30_std_unique_ptr/main.cpp
index 9b98b5794..68654cd84 100644
--- a/exercises/30_std_unique_ptr/main.cpp
+++ b/exercises/30_std_unique_ptr/main.cpp
@@ -48,13 +48,21 @@ int main(int argc, char **argv) {
     problems[2] = std::move(RECORDS);
 
     // ---- 不要修改以上代码 ----
+    for (int i = 0; i < 3; ++i) {
+    std::cout << "problems[" << i << "]: ";
+    for (auto const &record : problems[i]) {
+        std::cout << '"' << record << "\" ";
+    }
+    std::cout << '\n';
+}
+
 
     std::vector<const char *> answers[]{
         {"fd"},
         // TODO: 分析 problems[1] 中资源的生命周期，将记录填入 `std::vector`
         // NOTICE: 此题结果依赖对象析构逻辑，平台相关，提交时以 CI 实际运行平台为准
-        {"", "", "", "", "", "", "", ""},
-        {"", "", "", "", "", "", "", ""},
+    {"d", "ffr"},
+    {"d", "d", "r"},
     };
 
     // ---- 不要修改以下代码 ----
diff --git a/exercises/31_std_shared_ptr/main.cpp b/exercises/31_std_shared_ptr/main.cpp
index febbbcc6f..f33196df1 100644
--- a/exercises/31_std_shared_ptr/main.cpp
+++ b/exercises/31_std_shared_ptr/main.cpp
@@ -4,42 +4,41 @@
 // READ: `std::shared_ptr` <https://zh.cppreference.com/w/cpp/memory/shared_ptr>
 // READ: `std::weak_ptr` <https://zh.cppreference.com/w/cpp/memory/weak_ptr>
 
-// TODO: 将下列 `?` 替换为正确的值
 int main(int argc, char **argv) {
     auto shared = std::make_shared<int>(10);
     std::shared_ptr<int> ptrs[]{shared, shared, shared};
 
     std::weak_ptr<int> observer = shared;
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 4, "");
 
     ptrs[0].reset();
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 3, "");
 
     ptrs[1] = nullptr;
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 2, "");
 
     ptrs[2] = std::make_shared<int>(*shared);
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 1, "");
 
     ptrs[0] = shared;
     ptrs[1] = shared;
     ptrs[2] = std::move(shared);
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 3, "");
 
     std::ignore = std::move(ptrs[0]);
     ptrs[1] = std::move(ptrs[1]);
     ptrs[1] = std::move(ptrs[2]);
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 2, "");
 
     shared = observer.lock();
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 3, "");
 
     shared = nullptr;
     for (auto &ptr : ptrs) ptr = nullptr;
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 0, "");
 
     shared = observer.lock();
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 0, "");
 
     return 0;
-}
+}
\ No newline at end of file
diff --git a/exercises/32_std_transform/main.cpp b/exercises/32_std_transform/main.cpp
index f4dc25a5c..01df5e3df 100644
--- a/exercises/32_std_transform/main.cpp
+++ b/exercises/32_std_transform/main.cpp
@@ -1,5 +1,6 @@
 #include "../exercise.h"
 #include <algorithm>
+#include <sstream>
 #include <string>
 #include <vector>
 
@@ -8,8 +9,11 @@
 
 int main(int argc, char **argv) {
     std::vector<int> val{8, 13, 21, 34, 55};
+    std::vector<std::string> ans;
     // TODO: 调用 `std::transform`，将 `v` 中的每个元素乘以 2，并转换为字符串，存入 `ans`
-    // std::vector<std::string> ans
+    std::transform(val.begin(), val.end(), std::back_inserter(ans), [](int x){
+        std::ostringstream oss; oss << x * 2; return oss.str();
+    });
     ASSERT(ans.size() == val.size(), "ans size should be equal to val size");
     ASSERT(ans[0] == "16", "ans[0] should be 16");
     ASSERT(ans[1] == "26", "ans[1] should be 26");
diff --git a/exercises/33_std_accumulate/main.cpp b/exercises/33_std_accumulate/main.cpp
index 6326929d5..6f4649072 100644
--- a/exercises/33_std_accumulate/main.cpp
+++ b/exercises/33_std_accumulate/main.cpp
@@ -11,7 +11,9 @@ int main(int argc, char **argv) {
     //       - 形状为 shape；
     //       - 连续存储；
     //       的张量占用的字节数
-    // int size =
+    int size = 1;
+    for (auto d : shape) size *= d;
+    size *= sizeof(DataType);
     ASSERT(size == 602112, "4x1x3x224x224 = 602112");
     return 0;
 }