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..5d73fa231 100644
--- a/exercises/01_variable&add/main.cpp
+++ b/exercises/01_variable&add/main.cpp
@@ -5,6 +5,7 @@
 int main(int argc, char **argv) {
     // TODO: 补全变量定义并打印加法运算
     // x ?
+    int x=3;
     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..0ff2e2d54 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 99");
     std::cout << "befor func call: " << arg << std::endl;
     func(arg);
-    ASSERT(arg == ?, "arg should be ?");
+    ASSERT(arg == 99, "arg should be 99");
     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 99");
     std::cout << "befor add: " << param << std::endl;
     param += 1;
-    ASSERT(param == ?, "param should be ?");
+    ASSERT(param == 100, "param should be 100");
     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..2474ff6a7 100644
--- a/exercises/05_constexpr/main.cpp
+++ b/exercises/05_constexpr/main.cpp
@@ -1,14 +1,25 @@
 #include "../exercise.h"
 
-constexpr unsigned long long fibonacci(int i) {
-    switch (i) {
-        case 0:
-            return 0;
-        case 1:
-            return 1;
-        default:
-            return fibonacci(i - 1) + fibonacci(i - 2);
+// constexpr unsigned long long fibonacci(int i) {
+//     switch (i) {
+//         case 0:
+//             return 0;
+//         case 1:
+//             return 1;
+//         default:
+//             return fibonacci(i - 1) + fibonacci(i - 2);
+//     }
+// }
+
+constexpr unsigned long long fibonacci(int n) {
+    if (n <= 1) return n;
+    unsigned long long a = 0, b = 1;
+    for (int i = 2; i <= n; ++i) {
+        auto temp = a + b;
+        a = b;
+        b = temp;
     }
+    return b;
 }
 
 int main(int argc, char **argv) {
@@ -19,7 +30,7 @@ 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);
+    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..07e7ea883 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 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..97133a98a 100644
--- a/exercises/07_loop/main.cpp
+++ b/exercises/07_loop/main.cpp
@@ -5,9 +5,10 @@
 // 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]{0, 1};
     // TODO: 设置正确的循环条件
-    for (; false; ++cached) {
+    static int cached = 2;
+    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..78c7deeed 100644
--- a/exercises/08_pointer/main.cpp
+++ b/exercises/08_pointer/main.cpp
@@ -5,6 +5,12 @@ 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..7f9104283 100644
--- a/exercises/09_enum&union/main.cpp
+++ b/exercises/09_enum&union/main.cpp
@@ -37,7 +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..2d5d89542 100644
--- a/exercises/10_trivial/main.cpp
+++ b/exercises/10_trivial/main.cpp
@@ -9,8 +9,13 @@ 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];
+    if (cache.cached == 0) {
+        cache.cache[0] = 0;
+        cache.cache[1] = 1;
+        cache.cached = 2;
+    }
+    for (; cache.cached <= i; ++cache.cached) {
+        cache.cache[cache.cached] = cache.cache[cache.cached - 1] + cache.cache[cache.cached - 2];
     }
     return cache.cache[i];
 }
@@ -19,7 +24,7 @@ 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{};
     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..b03bb11b7 100644
--- a/exercises/11_method/main.cpp
+++ b/exercises/11_method/main.cpp
@@ -3,10 +3,10 @@
 struct Fibonacci {
     unsigned long long cache[128];
     int cached;
-
+    Fibonacci() : cache{0, 1}, cached(2) {}
     // 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) {
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];
diff --git a/exercises/12_method_const/main.cpp b/exercises/12_method_const/main.cpp
index 5521be4da..36ed8c28c 100644
--- a/exercises/12_method_const/main.cpp
+++ b/exercises/12_method_const/main.cpp
@@ -5,7 +5,11 @@
 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) {
+    // }
+        // 修改为 constexpr const 成员函数，支持编译期调用
+    constexpr int get(int i) const {
+        return numbers[i];
     }
 };
 
diff --git a/exercises/13_class/main.cpp b/exercises/13_class/main.cpp
index 9afa98c5b..b53da318d 100644
--- a/exercises/13_class/main.cpp
+++ b/exercises/13_class/main.cpp
@@ -15,10 +15,10 @@ class Fibonacci {
 public:
     // TODO: 实现构造器
     // Fibonacci()
-
+    Fibonacci() : cache{0, 1}, cached(2) {}
     // TODO: 实现正确的缓存优化斐波那契计算
     size_t get(int i) {
-        for (; false; ++cached) {
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];
diff --git a/exercises/14_class_destruct/main.cpp b/exercises/14_class_destruct/main.cpp
index 42150e8ca..9beca9cc1 100644
--- a/exercises/14_class_destruct/main.cpp
+++ b/exercises/14_class_destruct/main.cpp
@@ -8,17 +8,26 @@
 class DynFibonacci {
     size_t *cache;
     int cached;
+    int capacity;     // 缓存容量（用于防止越界）
 
 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(2), capacity(capacity) {
+        cache[0] = 0;
+        cache[1] = 1;
+    }
 
     // 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) {
+        ASSERT(i < capacity, "Index out of bounds");
+
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];
diff --git a/exercises/15_class_clone/main.cpp b/exercises/15_class_clone/main.cpp
index f74b70391..8c8fdec41 100644
--- a/exercises/15_class_clone/main.cpp
+++ b/exercises/15_class_clone/main.cpp
@@ -7,20 +7,33 @@
 class DynFibonacci {
     size_t *cache;
     int cached;
+    int capacity;
 
 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(2), capacity(capacity) {
+        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.capacity]), cached(other.cached), capacity(other.capacity) {
+        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) {
+        ASSERT(i < capacity, "i out of bounds");
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];
diff --git a/exercises/16_class_move/main.cpp b/exercises/16_class_move/main.cpp
index 8d2c421da..ec5d6bf81 100644
--- a/exercises/16_class_move/main.cpp
+++ b/exercises/16_class_move/main.cpp
@@ -12,24 +12,50 @@
 class DynFibonacci {
     size_t *cache;
     int cached;
+    int capacity;
 
 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(2), capacity(capacity) {
+        cache[0] = 0;
+        cache[1] = 1;
+    }
 
     // TODO: 实现移动构造器
-    DynFibonacci(DynFibonacci &&) noexcept = delete;
+    DynFibonacci(DynFibonacci &&other) noexcept
+        : cache(other.cache), cached(other.cached), capacity(other.capacity) {
+        other.cache = nullptr;
+        other.cached = 0;
+        other.capacity = 0;
+    }
 
     // TODO: 实现移动赋值
     // NOTICE: ⚠ 注意移动到自身问题 ⚠
-    DynFibonacci &operator=(DynFibonacci &&) noexcept = delete;
+    DynFibonacci &operator=(DynFibonacci &&other) noexcept {
+        if (this != &other) {
+            delete[] cache;
+
+            cache = other.cache;
+            cached = other.cached;
+            capacity = other.capacity;
+
+            other.cache = nullptr;
+            other.cached = 0;
+            other.capacity = 0;
+        }
+        return *this;
+    }
 
     // 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 operator[](int i) {
-        for (; false; ++cached) {
+        ASSERT(i < capacity, "Index out of bounds");
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];
diff --git a/exercises/17_class_derive/main.cpp b/exercises/17_class_derive/main.cpp
index 819ae72fc..0c245df4f 100644
--- a/exercises/17_class_derive/main.cpp
+++ b/exercises/17_class_derive/main.cpp
@@ -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) == 4, "There is an int in X");
+    static_assert(sizeof(A) == 4, "There is an int in A");
+    static_assert(sizeof(B) == 8, "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..344709e4c 100644
--- a/exercises/18_class_virtual/main.cpp
+++ b/exercises/18_class_virtual/main.cpp
@@ -42,38 +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;
 }
diff --git a/exercises/19_class_virtual_destruct/main.cpp b/exercises/19_class_virtual_destruct/main.cpp
index cdd54f74f..2caf9ab75 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; // 类内仅声明，类外定义初始化
 
     A() {
         ++num_a;
     }
-    ~A() {
+    virtual ~A() {   // 需要虚析构，确保通过基类指针删除派生对象时行为正确
         --num_a;
     }
 
@@ -20,12 +20,12 @@ struct A {
 };
 struct B final : public A {
     // TODO: 正确初始化静态字段
-    static int num_b = 0;
+    static int num_b; // 类内仅声明，类外定义初始化
 
     B() {
         ++num_b;
     }
-    ~B() {
+    ~B() override {
         --num_b;
     }
 
@@ -34,13 +34,17 @@ struct B final : public A {
     }
 };
 
+// —— 静态成员的类外定义与初始化 ——
+int A::num_a = 0;
+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 +52,13 @@ 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..4abc7e34e 100644
--- a/exercises/20_function_template/main.cpp
+++ b/exercises/20_function_template/main.cpp
@@ -2,7 +2,8 @@
 
 // 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) {
+template <typename T>
+T plus(T a, T b) {
     return a + b;
 }
 
@@ -14,7 +15,8 @@ int main(int argc, char **argv) {
     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?");
+    // 使用误差容忍判断浮点数
+    ASSERT(std::abs(plus(0.1, 0.2) - 0.3) < 1e-9, "How to make this pass?");
 
     return 0;
 }
diff --git a/exercises/21_runtime_datatype/main.cpp b/exercises/21_runtime_datatype/main.cpp
index 9c4bf376a..aaed5d31e 100644
--- a/exercises/21_runtime_datatype/main.cpp
+++ b/exercises/21_runtime_datatype/main.cpp
@@ -18,13 +18,24 @@ struct TaggedUnion {
 };
 
 // TODO: 将这个函数模板化用于 sigmoid_dyn
-float sigmoid(float x) {
+// 模板化 sigmoid 函数，支持 float 与 double
+template <typename T>
+T sigmoid(T x) {
     return 1 / (1 + std::exp(-x));
 }
 
+// 动态派发 sigmoid
 TaggedUnion sigmoid_dyn(TaggedUnion x) {
     TaggedUnion ans{x.type};
     // TODO: 根据 type 调用 sigmoid
+    switch (x.type) {
+        case DataType::Float:
+            ans.f = sigmoid(x.f);
+            break;
+        case DataType::Double:
+            ans.d = sigmoid(x.d);
+            break;
+    }
     return ans;
 }
 
diff --git a/exercises/22_class_template/main.cpp b/exercises/22_class_template/main.cpp
index d4985d904..81a3d6d6c 100644
--- a/exercises/22_class_template/main.cpp
+++ b/exercises/22_class_template/main.cpp
@@ -10,6 +10,10 @@ 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 (int i = 0; i < 4; ++i) {
+            shape[i] = shape_[i];
+            size *= shape_[i];
+        }
         data = new T[size];
         std::memcpy(data, data_, size * sizeof(T));
     }
@@ -28,6 +32,45 @@ struct Tensor4D {
     // 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
+        // 1) 形状检查，并计算 this 总元素数
+        unsigned int total = 1;
+        for (int i = 0; i < 4; ++i) {
+            ASSERT(others.shape[i] == 1 || others.shape[i] == shape[i], "Broadcast shape mismatch");
+            total *= shape[i];
+        }
+
+        // 2) 计算 this 的标准行主序 stride
+        unsigned int self_stride[4];
+        self_stride[3] = 1;
+        for (int i = 2; i >= 0; --i) {
+            self_stride[i] = self_stride[i + 1] * shape[i + 1];
+        }
+
+        // 3) 先计算 others 的“标准 stride”（忽略广播），再逐维应用“为 1 则置 0”的规则
+        unsigned int other_stride_base[4];
+        other_stride_base[3] = 1;
+        for (int i = 2; i >= 0; --i) {
+            other_stride_base[i] = other_stride_base[i + 1] * others.shape[i + 1];
+        }
+        unsigned int other_stride[4];
+        for (int i = 0; i < 4; ++i) {
+            other_stride[i] = (others.shape[i] == 1) ? 0u : other_stride_base[i];
+        }
+
+        // 4) 逐元素：把 this 的线性下标解码为 4D 坐标，再映射到 others 的线性下标
+        for (unsigned int lin = 0; lin < total; ++lin) {
+            unsigned int idx = lin;
+            unsigned int coord[4];
+            for (int d = 0; d < 4; ++d) {
+                coord[d] = idx / self_stride[d];
+                idx %= self_stride[d];
+            }
+            unsigned int oidx = 0;
+            for (int d = 0; d < 4; ++d) {
+                oidx += coord[d] * other_stride[d];
+            }
+            data[lin] += others.data[oidx];
+        }
         return *this;
     }
 };
diff --git a/exercises/23_template_const/main.cpp b/exercises/23_template_const/main.cpp
index e0105e168..6fa3e4f5d 100644
--- a/exercises/23_template_const/main.cpp
+++ b/exercises/23_template_const/main.cpp
@@ -10,6 +10,10 @@ struct Tensor {
 
     Tensor(unsigned int const shape_[N]) {
         unsigned int size = 1;
+        for (unsigned int i = 0; i < N; ++i) {
+            shape[i] = shape_[i];
+            size *= shape[i];
+        }
         // TODO: 填入正确的 shape 并计算 size
         data = new T[size];
         std::memset(data, 0, size * sizeof(T));
@@ -32,9 +36,12 @@ struct Tensor {
 private:
     unsigned int data_index(unsigned int const indices[N]) const {
         unsigned int index = 0;
-        for (unsigned int i = 0; i < N; ++i) {
+        unsigned int stride = 1;
+        for (int i = N - 1; i >= 0; --i) {
             ASSERT(indices[i] < shape[i], "Invalid index");
             // TODO: 计算 index
+            index += indices[i] * stride;
+            stride *= shape[i];
         }
         return index;
     }
diff --git a/exercises/24_std_array/main.cpp b/exercises/24_std_array/main.cpp
index c29718d9d..1d645c8d4 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) == sizeof(int) * 5, "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) == sizeof(double) * 8, "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) == sizeof(char) * 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..047067e1f 100644
--- a/exercises/25_std_vector/main.cpp
+++ b/exercises/25_std_vector/main.cpp
@@ -8,81 +8,83 @@
 int main(int argc, char **argv) {
     {
         std::vector<int> vec{1, 2, 3, 4, 5};
-        ASSERT(vec.size() == ?, "Fill in the correct value.");
+        ASSERT(vec.size() == 5, "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.");
+        // sizeof(vec) 是 vector 类对象本身的大小，不包括数据容量
+        ASSERT(sizeof(vec) == sizeof(std::vector<int>), "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) == sizeof(std::vector<double>), "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) == sizeof(std::vector<double>), "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) == sizeof(std::vector<double>), "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);
+            // 插入位置在开头，时间复杂度 O(n)
+            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.erase(vec.begin() + 3);  // 删除值为 3 的元素
             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.");
+            vec.shrink_to_fit(); // 容量缩减到正好大小
+            ASSERT(vec.capacity() == vec.size(), "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."); // 容量不变
         }
     }
     {
-        std::vector<char> vec(?, ?); // TODO: 调用正确的构造函数
+        std::vector<char> vec(48, 'z'); // TODO: 调用正确的构造函数
         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) == sizeof(std::vector<char>), "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.");
+            vec.resize(16); // 缩小 size，不影响 capacity
+            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.");
+            vec.reserve(256); // 提前分配更大的内存
+            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.");
         }
     }
 
diff --git a/exercises/26_std_vector_bool/main.cpp b/exercises/26_std_vector_bool/main.cpp
index b4ab4f9c4..47ce69630 100644
--- a/exercises/26_std_vector_bool/main.cpp
+++ b/exercises/26_std_vector_bool/main.cpp
@@ -4,31 +4,32 @@
 // READ: std::vector <https://zh.cppreference.com/w/cpp/container/vector_bool>
 // READ: 模板特化 <https://zh.cppreference.com/w/cpp/language/template_specialization>
 
-// 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); // TODO: 正确调用构造函数
     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`");
+        auto ref = vec[30];  // 注意这里返回的是 std::vector<bool>::reference（代理类）
+        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..f85e60a55 100644
--- a/exercises/27_strides/main.cpp
+++ b/exercises/27_strides/main.cpp
@@ -15,9 +15,12 @@ using udim = unsigned int;
 /// @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());
-    // 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
+    udim stride = 1;
+    // 从最后一维开始逆向计算步长
+    for (int i = static_cast<int>(shape.size()) - 1; i >= 0; --i) {
+        strides[i] = stride;
+        stride *= shape[i]; // 累积形状元素，作为前一维的步长
+    }
     return strides;
 }
 
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..2997390b0 100644
--- a/exercises/29_std_map/main.cpp
+++ b/exercises/29_std_map/main.cpp
@@ -6,12 +6,14 @@
 
 template<class k, class v>
 bool key_exists(std::map<k, v> const &map, k const &key) {
-    // TODO: 实现函数
+    // 使用 count 或 find 判断 key 是否存在
+    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
+    // 插入或更新键值对
+    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..e07531b27 100644
--- a/exercises/30_std_unique_ptr/main.cpp
+++ b/exercises/30_std_unique_ptr/main.cpp
@@ -51,12 +51,11 @@ int main(int argc, char **argv) {
 
     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
-        {"", "", "", "", "", "", "", ""},
-        {"", "", "", "", "", "", "", ""},
+        // 分析 problems[1] 中资源的生命周期
+        {"f", "fd"},
+        // 分析 problems[2] 中资源的生命周期
+        {"d", "d", "rd"},
     };
-
     // ---- 不要修改以下代码 ----
 
     for (auto i = 0; i < 3; ++i) {
diff --git a/exercises/31_std_shared_ptr/main.cpp b/exercises/31_std_shared_ptr/main.cpp
index febbbcc6f..99c540e19 100644
--- a/exercises/31_std_shared_ptr/main.cpp
+++ b/exercises/31_std_shared_ptr/main.cpp
@@ -10,36 +10,36 @@ int main(int argc, char **argv) {
     std::shared_ptr<int> ptrs[]{shared, shared, shared};
 
     std::weak_ptr<int> observer = shared;
-    ASSERT(observer.use_count() == ?, "");
+    ASSERT(observer.use_count() == 4, "");  // shared + 3 个数组元素
 
     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() == ?, "");
+    ptrs[2] = std::make_shared<int>(*shared); // ptrs[2] 改指向新对象，旧控制块 -1
+    ASSERT(observer.use_count() == 1, "");
 
-    ptrs[0] = shared;
-    ptrs[1] = shared;
-    ptrs[2] = std::move(shared);
-    ASSERT(observer.use_count() == ?, "");
+    ptrs[0] = shared;            // +1 → 2
+    ptrs[1] = shared;            // +1 → 3
+    ptrs[2] = std::move(shared); // 接管 shared（shared 清空），总数仍 3
+    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() == ?, "");
+    std::ignore = std::move(ptrs[0]); // 清空 ptrs[0] → 2
+    ptrs[1] = std::move(ptrs[1]);     // 自我移动，无变化 → 2
+    ptrs[1] = std::move(ptrs[2]);     // 合并所有权：先释放自身(-1)再接管(+0)，最终只剩 1
+    ASSERT(observer.use_count() == 2, "");
 
-    shared = observer.lock();
-    ASSERT(observer.use_count() == ?, "");
+    shared = observer.lock();         // 再拿一份强引用 → 2
+    ASSERT(observer.use_count() == 3, "");
 
     shared = nullptr;
-    for (auto &ptr : ptrs) ptr = nullptr;
-    ASSERT(observer.use_count() == ?, "");
+    for (auto &ptr : ptrs) ptr = nullptr; // 把最后那份也清了 → 0
+    ASSERT(observer.use_count() == 0, "");
 
-    shared = observer.lock();
-    ASSERT(observer.use_count() == ?, "");
+    shared = observer.lock();         // 对象已析构，拿不到 → 0
+    ASSERT(observer.use_count() == 0, "");
 
     return 0;
 }
diff --git a/exercises/32_std_transform/main.cpp b/exercises/32_std_transform/main.cpp
index f4dc25a5c..c2297ff8c 100644
--- a/exercises/32_std_transform/main.cpp
+++ b/exercises/32_std_transform/main.cpp
@@ -8,8 +8,13 @@
 
 int main(int argc, char **argv) {
     std::vector<int> val{8, 13, 21, 34, 55};
+    
     // 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::vector<std::string> ans(val.size());
+
+    std::transform(val.begin(), val.end(), ans.begin(),
+                   [](int x) { return std::to_string(x * 2); });
+
     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..921afe11d 100644
--- a/exercises/33_std_accumulate/main.cpp
+++ b/exercises/33_std_accumulate/main.cpp
@@ -12,6 +12,8 @@ int main(int argc, char **argv) {
     //       - 连续存储；
     //       的张量占用的字节数
     // int size =
+    // 使用 std::accumulate 计算张量元素个数（1×3×224×224），再乘以 sizeof(DataType)
+    int size = std::accumulate(std::begin(shape), std::end(shape), sizeof(DataType), std::multiplies<int>());
     ASSERT(size == 602112, "4x1x3x224x224 = 602112");
     return 0;
 }