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..52c6281d5 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 = 42;
     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..8084b9e18 100644
--- a/exercises/05_constexpr/main.cpp
+++ b/exercises/05_constexpr/main.cpp
@@ -18,9 +18,11 @@ 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_N = 10;
     constexpr auto ANS = fibonacci(ANS_N);
     std::cout << "fibonacci(" << ANS_N << ") = " << ANS << std::endl;
 
     return 0;
 }
+
+//constexpr 会让常量的数据在编译时就计算出来数据
\ No newline at end of file
diff --git a/exercises/06_array/main.cpp b/exercises/06_array/main.cpp
index 61ed99ec0..3e54b2ab8 100644
--- a/exercises/06_array/main.cpp
+++ b/exercises/06_array/main.cpp
@@ -11,13 +11,15 @@ 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] != 0 ? 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");
+    //std::cout << sizeof(arr) << std::endl;
+    //90个unsigned long long类型的元素，每个元素8字节，共720字节
+    ASSERT(sizeof(arr) == 720, "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..d02ddfd49 100644
--- a/exercises/07_loop/main.cpp
+++ b/exercises/07_loop/main.cpp
@@ -5,9 +5,12 @@
 // 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}, cached = 2;
     // TODO: 设置正确的循环条件
-    for (; false; ++cached) {
+    if (i < cached) {
+        return cache[i];
+    }
+    for (; i>= cached; ++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..99a41b3b8 100644
--- a/exercises/08_pointer/main.cpp
+++ b/exercises/08_pointer/main.cpp
@@ -5,6 +5,11 @@ 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 < len - 2; i++) {
+        if (*(ptr + (i + 2) * stride) != *(ptr + i * stride) + *(ptr + (i + 1) * stride)) {
+            return false;
+        }
+    }
     return true;
 }
 
diff --git a/exercises/09_enum&union/main.cpp b/exercises/09_enum&union/main.cpp
index 3f2cec768..bb71725bb 100644
--- a/exercises/09_enum&union/main.cpp
+++ b/exercises/09_enum&union/main.cpp
@@ -35,8 +35,28 @@ ColorEnum convert_by_pun(Color c) {
         Color c;
     };
 
-    TypePun pun;
+    static TypePun pun;
+    //不使用静态编译会有警告因为尝试返回局部变量的引用
     // TODO: 补全类型双关转换
+    switch (c) {
+        case Color::Red:
+            pun.c = Color::Red;
+            pun.e = COLOR_RED;
+            break;
+        case Color::Green:
+            pun.c = Color::Green;
+            pun.e = COLOR_GREEN;
+            break;
+        case Color::Yellow:
+            pun.c = Color::Yellow;
+            pun.e = COLOR_YELLOW;
+            break;
+        case Color::Blue:
+            pun.c = Color::Blue;
+            pun.e = COLOR_BLUE;
+            break;
+    }
+
 
     return pun.e;
 }
diff --git a/exercises/10_trivial/main.cpp b/exercises/10_trivial/main.cpp
index 6ba23e48e..e82860eb5 100644
--- a/exercises/10_trivial/main.cpp
+++ b/exercises/10_trivial/main.cpp
@@ -9,8 +9,12 @@ 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];
+    int cached = cache.cached;
+    if (i < cached) {
+        return cache.cache[i];
+    }
+    for (; cached <= i; ++cached) {
+        cache.cache[cached] = cache.cache[cached - 1] + cache.cache[cached - 2];
     }
     return cache.cache[i];
 }
@@ -20,6 +24,9 @@ int main(int argc, char **argv) {
     // 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;
+    fib.cache[0] = 0;
+    fib.cache[1] = 1;
+    fib.cached = 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..9c32ee716 100644
--- a/exercises/11_method/main.cpp
+++ b/exercises/11_method/main.cpp
@@ -6,16 +6,20 @@ 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) {
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];
     }
 };
+//结构里的变量是可以直接访问的
 
 int main(int argc, char **argv) {
     // TODO: 初始化缓存结构体，使计算正确
     Fibonacci fib;
+    fib.cache[0] = 0;
+    fib.cache[1] = 1;
+    fib.cached = 2;
     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..c0ffa5eb5 100644
--- a/exercises/12_method_const/main.cpp
+++ b/exercises/12_method_const/main.cpp
@@ -5,13 +5,33 @@
 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];
     }
+    //一定要加const修饰符 非 const 成员函数不能被 const 对象调用。
 };
 
 int main(int argc, char **argv) {
     Fibonacci constexpr FIB{{0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55}};
+    //是结构体的一种声明方式
     ASSERT(FIB.get(10) == 55, "fibonacci(10) should be 55");
     std::cout << "fibonacci(10) = " << FIB.get(10) << std::endl;
     return 0;
 }
+
+/*
+struct Point {
+    int x;
+    int y;
+};
+
+int main() {
+    constexpr Point p{3, 4};          // ✅ 聚合初始化
+    // 或者更明确一点：
+    constexpr Point q = {10, 20};     // ✅ 等价写法
+
+    std::cout << p.x << ", " << p.y << std::endl; // 输出: 3, 4
+}
+看起来也是跟python类似的结构体初始化
+
+*/
\ No newline at end of file
diff --git a/exercises/13_class/main.cpp b/exercises/13_class/main.cpp
index 9afa98c5b..b689cb2af 100644
--- a/exercises/13_class/main.cpp
+++ b/exercises/13_class/main.cpp
@@ -15,10 +15,15 @@ class Fibonacci {
 public:
     // TODO: 实现构造器
     // Fibonacci()
+    Fibonacci(){
+        cache[0] = 0;
+        cache[1] = 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..0cf5473fa 100644
--- a/exercises/14_class_destruct/main.cpp
+++ b/exercises/14_class_destruct/main.cpp
@@ -11,14 +11,20 @@ class DynFibonacci {
 
 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(0) { 
+        cache[0] = 0;
+        cache[1] = 1;
+        cached = 2;
+    }
 
     // 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) {
+        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..9546cef41 100644
--- a/exercises/15_class_clone/main.cpp
+++ b/exercises/15_class_clone/main.cpp
@@ -7,20 +7,35 @@
 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(0), capacity(capacity) {
+        cache[0] = 0;
+        cache[1] = 1;
+        cached = 2;
+    }
 
     // TODO: 实现复制构造器
-    DynFibonacci(DynFibonacci const &) = delete;
+    DynFibonacci(const DynFibonacci& other)
+        : capacity(other.capacity)
+        , cached(other.cached)
+        , cache(new size_t[other.capacity])
+    {
+        // 深拷贝缓存内容
+        for (int i = 0; i < other.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) {
+        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..4d43b4560 100644
--- a/exercises/16_class_move/main.cpp
+++ b/exercises/16_class_move/main.cpp
@@ -12,24 +12,45 @@
 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(0), capacity(capacity) {
+        cache[0] = 0;
+        cache[1] = 1;
+        cached = 2;
+    }
     // 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) {
+        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..67b3b3b41 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
@@ -67,7 +67,8 @@ int main(int argc, char **argv) {
     // THINK: 观察打印出的信息，推测把大象放进冰箱分几步？
     // THINK: 这样的代码是“安全”的吗？
     // NOTICE: 真实场景中不太可能出现这样的代码
-
+//可以简单理解成先创建了一个临时变量 B(5)，然后把这个临时变量的 A 部分拷贝到 ab 中
+//之后这个B(5)的临时变量就被销毁了
     i = 0;
     std::cout << std::endl
               << "-------------------------" << std::endl
diff --git a/exercises/18_class_virtual/main.cpp b/exercises/18_class_virtual/main.cpp
index ac6382413..add360de5 100644
--- a/exercises/18_class_virtual/main.cpp
+++ b/exercises/18_class_virtual/main.cpp
@@ -42,38 +42,44 @@ 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);
+    //上面都定义了自己的虚函数 所以会重写
+    ASSERT(d.virtual_name() == 'C', MSG);
+    //d派生自c c的虚函数被final修饰 所以不会被重写
+    ASSERT(a.direct_name() == 'A', MSG);
+    ASSERT(b.direct_name() == 'B', MSG);
+    ASSERT(c.direct_name() == 'C', MSG);
+    ASSERT(d.direct_name() == 'D', MSG);
+    //direct_name不是虚函数 所以不会重写
 
     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);
+    //这个是根据对象的实际类型决定的 rab 静态类型 A&，实际对象是 B 类型 所以调用 B 的 virtual_name
+    ASSERT(rbc.virtual_name() == 'C', MSG);
+    ASSERT(rcd.virtual_name() == 'C', MSG);
+
+    ASSERT(rab.direct_name() == 'A', MSG);
+    //这个会根据引用的静态类型决定的 rab 静态类型 A&，所以调用 A 的 direct_name
+    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..efe7a4208 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;
     }
 
@@ -20,7 +20,7 @@ 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;
 
     B() {
         ++num_b;
@@ -34,13 +34,16 @@ struct B final : public A {
     }
 };
 
+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;
@@ -48,14 +51,15 @@ 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()");
+    std::cout << "A::num_a = " << A::num_a << ", B::num_b = " << B::num_b << std::endl;
+    //需要添加虚函数析构器 否则通过基类指针删除派生类对象时不会调用派生类的析构器
     // 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
     ASSERT(A::num_a == 0, "Every A was destroyed");
diff --git a/exercises/20_function_template/main.cpp b/exercises/20_function_template/main.cpp
index cb6d978d3..c0093b614 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 +15,7 @@ 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?");
+    ASSERT(plus(0.1, 0.2) - 0.3  < 0.1, "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..ff913a79c 100644
--- a/exercises/21_runtime_datatype/main.cpp
+++ b/exercises/21_runtime_datatype/main.cpp
@@ -18,13 +18,25 @@ struct TaggedUnion {
 };
 
 // TODO: 将这个函数模板化用于 sigmoid_dyn
-float sigmoid(float x) {
+template <typename T>
+T sigmoid(T x) {
     return 1 / (1 + std::exp(-x));
 }
 
 TaggedUnion sigmoid_dyn(TaggedUnion x) {
     TaggedUnion ans{x.type};
     // TODO: 根据 type 调用 sigmoid
+    switch (ans.type) {
+        case DataType::Float:
+            ans.f = sigmoid(x.f);
+            break;
+        case DataType::Double:
+            ans.d = sigmoid(x.d);
+            break;
+        default:
+            ASSERT(false, "Unsupported type for sigmoid");
+    }
+//因为返回要赋值的地方不同所以要用switch
     return ans;
 }
 
diff --git a/exercises/22_class_template/main.cpp b/exercises/22_class_template/main.cpp
index d4985d904..da6843064 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));
     }
@@ -27,7 +31,27 @@ struct Tensor4D {
     // 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
+        for (unsigned int n = 0; n < shape[0]; ++n)
+        for (unsigned int c = 0; c < shape[1]; ++c)
+        for (unsigned int h = 0; h < shape[2]; ++h)
+        for (unsigned int w = 0; w < shape[3]; ++w) {
+            unsigned int this_idx = n * (shape[1]*shape[2]*shape[3])
+                                  + c * (shape[2]*shape[3])
+                                  + h * shape[3]
+                                  + w;
+
+            unsigned int on = (others.shape[0] == 1) ? 0 : n;
+            unsigned int oc = (others.shape[1] == 1) ? 0 : c;
+            unsigned int oh = (others.shape[2] == 1) ? 0 : h;
+            unsigned int ow = (others.shape[3] == 1) ? 0 : w;
+
+            unsigned int other_idx = on * (others.shape[1]*others.shape[2]*others.shape[3])
+                                   + oc * (others.shape[2]*others.shape[3])
+                                   + oh * others.shape[3]
+                                   + ow;
+
+            data[this_idx] += others.data[other_idx];
+        }
         return *this;
     }
 };
diff --git a/exercises/23_template_const/main.cpp b/exercises/23_template_const/main.cpp
index e0105e168..c35ddd595 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 (int i = 0; i < N; ++i) {
+            shape[i] = shape_[i];
+            size *= shape_[i];
+        }
         data = new T[size];
         std::memset(data, 0, size * sizeof(T));
     }
@@ -31,12 +35,25 @@ 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) {
-            ASSERT(indices[i] < shape[i], "Invalid index");
-            // TODO: 计算 index
+            unsigned int index = 0;
+    unsigned int stride = 1;
+
+    // 从最后一个维度往前计算 stride（更高效）
+    // 但也可以从前往后：先算总 stride
+    // 这里采用从后往前预计算的方式，或直接在循环中累积
+
+    // 方法：从第0维到第N-1维，每一步乘以后续维度的大小
+    for (unsigned int i = 0; i < N; ++i) {
+        ASSERT(indices[i] < shape[i], "Invalid index");
+
+        // 计算当前维度之后所有维度的乘积（即 stride for dim i）
+        unsigned int dim_stride = 1;
+        for (unsigned int j = i + 1; j < N; ++j) {
+            dim_stride *= shape[j];
         }
-        return index;
+        index += indices[i] * dim_stride;
+    }
+    return index;
     }
 };
 
diff --git a/exercises/24_std_array/main.cpp b/exercises/24_std_array/main.cpp
index c29718d9d..1c99d7f5e 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) == 20, "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, 20) == 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) == 64, "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..6551686f7 100644
--- a/exercises/25_std_vector/main.cpp
+++ b/exercises/25_std_vector/main.cpp
@@ -8,81 +8,84 @@
 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.");
+        ASSERT(sizeof(vec) == 24, "Fill in the correct value.");
+        //这个统计的是三个指针的长度 3*8=24
         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);
+            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(?);
-            ASSERT((vec == std::vector<double>{1, 1.5, 2, 4, 6}), "Make this assertion pass.");
+            vec.erase(vec.begin() + 4);
+            std::cout << vec[4] << std::endl;
+            ASSERT((vec == std::vector<double>{1, 1.5, 2, 3, 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'); // 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) == 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.");
+            //resize会改变size但不会改变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.");
+            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..f7d2a7062 100644
--- a/exercises/26_std_vector_bool/main.cpp
+++ b/exercises/26_std_vector_bool/main.cpp
@@ -6,29 +6,34 @@
 
 // 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) == 40, "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`");
+        //ref 的类型不是 bool，而是 std::vector<bool>::reference —— 一个可修改原 vector 中 bit 的代理对象！
+        /*
+            bool b = vec[30]; // 显式转为 bool → 拷贝值
+b =         false;        // 不影响 vec[30]
+        */
         // 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..74bad98bf 100644
--- a/exercises/27_strides/main.cpp
+++ b/exercises/27_strides/main.cpp
@@ -14,11 +14,20 @@ 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());
-    // 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;
+    std::vector<udim> result(shape.size());
+    
+    // 从最后一个维度开始，stride = 1
+    udim stride = 1;
+    
+    // 逆向遍历 shape，同时正向填充 result（从后往前）
+    for (auto i = shape.rbegin(), end = shape.rend(); i != end; ++i) {
+        // 当前维度的 stride 是“后面所有维度大小的乘积”
+        // 我们从后往前填 result
+        result[std::distance(i, shape.rend()) - 1] = stride;
+        stride *= *i;
+    }
+    
+    return result;
 }
 
 // ---- 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..5fcfdf31d 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..9d01c8018 100644
--- a/exercises/29_std_map/main.cpp
+++ b/exercises/29_std_map/main.cpp
@@ -4,14 +4,14 @@
 // READ: `std::map` <https://zh.cppreference.com/w/cpp/container/map>
 // READ: `std::unordered_map` <https://zh.cppreference.com/w/cpp/container/unordered_map>
 
-template<class k, class v>
-bool key_exists(std::map<k, v> const &map, k const &key) {
-    // TODO: 实现函数
+template<class K, class V>
+bool key_exists(std::map<K, V> const &map, K const &key) {
+    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
+template<class K, class V>
+void set(std::map<K, V> &map, K key, V value) {
+    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..79e2db10a 100644
--- a/exercises/30_std_unique_ptr/main.cpp
+++ b/exercises/30_std_unique_ptr/main.cpp
@@ -19,15 +19,18 @@ class Resource {
     ~Resource() {
         RECORDS.push_back(_records);
     }
+    //析构时会把recards记录下来
 };
 
 using Unique = std::unique_ptr<Resource>;
 Unique reset(Unique ptr) {
     if (ptr) ptr->record('r');
+    //会调用析构
     return std::make_unique<Resource>();
 }
 Unique drop(Unique ptr) {
     if (ptr) ptr->record('d');
+    //会调用析构
     return nullptr;
 }
 Unique forward(Unique ptr) {
@@ -39,12 +42,15 @@ int main(int argc, char **argv) {
     std::vector<std::string> problems[3];
 
     drop(forward(reset(nullptr)));
+    // reset（nullptr)不会记录r 因为时空 之后析构  之后forword记录f 最后drop记录d 记 fd
     problems[0] = std::move(RECORDS);
 
     forward(drop(reset(forward(forward(reset(nullptr))))));
+    //reset 空指针不记录r 两次forwar 记录 ff reset记录 ffr 就会写入因为rest会重新创建  d
     problems[1] = std::move(RECORDS);
 
     drop(drop(reset(drop(reset(reset(nullptr))))));
+    //reset 空指针不记录r  第二次的reset不是空记录记录 r 析构 d 就会d
     problems[2] = std::move(RECORDS);
 
     // ---- 不要修改以上代码 ----
@@ -53,8 +59,8 @@ int main(int argc, char **argv) {
         {"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 ----
@@ -62,6 +68,7 @@ int main(int argc, char **argv) {
     for (auto i = 0; i < 3; ++i) {
         ASSERT(problems[i].size() == answers[i].size(), "wrong size");
         for (auto j = 0; j < problems[i].size(); ++j) {
+            // NOTICE: 这里使用 std::
             ASSERT(std::strcmp(problems[i][j].c_str(), answers[i][j]) == 0, "wrong location");
         }
     }
diff --git a/exercises/31_std_shared_ptr/main.cpp b/exercises/31_std_shared_ptr/main.cpp
index febbbcc6f..8ec520812 100644
--- a/exercises/31_std_shared_ptr/main.cpp
+++ b/exercises/31_std_shared_ptr/main.cpp
@@ -8,38 +8,57 @@
 int main(int argc, char **argv) {
     auto shared = std::make_shared<int>(10);
     std::shared_ptr<int> ptrs[]{shared, shared, shared};
+    //共享指针  三个指针共享一个10个int的数组
 
     std::weak_ptr<int> observer = shared;
-    ASSERT(observer.use_count() == ?, "");
+    //弱引用不增加引用计数
+    ASSERT(observer.use_count() == 4, "");
+    //三个指针共享一个10个int的数组 所以引用计数为3
 
     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() == ?, "");
+    //会析构原来的引用让计数-1 
+    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, "");
+    if (ptrs[0] == nullptr) {
+        std::cout << "ptrs[0] is nullptr" << std::endl;
+    } else {
+        std::cout << "ptrs[0] is not nullptr" << std::endl;
+    }
 
+    std::cout << observer.use_count() << std::endl;
     std::ignore = std::move(ptrs[0]);
+    //auto temp = std::move(ptrs[0]);
+        if (ptrs[0] == nullptr) {
+        std::cout << "ptrs[0] is nullptr" << std::endl;
+    } else {
+        std::cout << "ptrs[0] is not nullptr" << std::endl;
+    }
+    //从打印看这个ignore并没有改变 甚至没有让ptrs[0]变成nullptr
+    std::cout << observer.use_count() << std::endl;
     ptrs[1] = std::move(ptrs[1]);
+    std::cout << observer.use_count() << std::endl;
     ptrs[1] = std::move(ptrs[2]);
-    ASSERT(observer.use_count() == ?, "");
+    std::cout << observer.use_count() << std::endl;
+    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;
 }
diff --git a/exercises/32_std_transform/main.cpp b/exercises/32_std_transform/main.cpp
index f4dc25a5c..5dec3ddc6 100644
--- a/exercises/32_std_transform/main.cpp
+++ b/exercises/32_std_transform/main.cpp
@@ -10,6 +10,12 @@ 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 v) {
+                       return std::to_string(v * 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..740810ab6 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 =
+    int size = std::accumulate(shape, shape + 4, 1, std::multiplies<int>()) * static_cast<int>(sizeof(DataType)) ;
+    std::cout << size << std::endl;
     ASSERT(size == 602112, "4x1x3x224x224 = 602112");
     return 0;
 }