finish exercises

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;
 }

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;
 }

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;
 }

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;
 }

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;
 }

exercises/05_constexpr/main.cpp

@@ -12,13 +12,13 @@ constexpr unsigned long long fibonacci(int i) {
 }
 
 int main(int argc, char **argv) {
-    constexpr auto FIB20 = fibonacci(20);
+    constexpr auto FIB20 = fibonacci(20);   
     ASSERT(FIB20 == 6765, "fibonacci(20) should be 6765");
     std::cout << "fibonacci(20) = " << FIB20 << std::endl;
 
     // 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 = 20;      // // constexpr 在编译器执行，会进入指数级递归，非常慢，大概率卡死或栈溢出
     constexpr auto ANS = fibonacci(ANS_N);
     std::cout << "fibonacci(" << ANS_N << ") = " << ANS << std::endl;
 

exercises/06_array/main.cpp

@@ -10,14 +10,14 @@ unsigned long long fibonacci(int i) {
         case 1:
             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));
+            // TODO: 补全三目表达式缺失的部分; 如果 arr[i] 已经被计算过就直接返回，否则计算后存入 arr[i]
+            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");

exercises/07_loop/main.cpp

@@ -5,9 +5,9 @@
 // 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) {
+    for (; cached <= i; ++cached) {
         cache[cached] = cache[cached - 1] + cache[cached - 2];
     }
     return cache[i];

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;
 }
 

exercises/09_enum&union/main.cpp

@@ -34,10 +34,10 @@ ColorEnum convert_by_pun(Color c) {
         ColorEnum e;
         Color c;
     };
-
+    
     TypePun pun;
     // TODO: 补全类型双关转换
-
+    pun.c = c;
     return pun.e;
 }
 

exercises/10_trivial/main.cpp

@@ -9,17 +9,17 @@ 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) {
+        cache.cache[cache.cached] =  cache.cache[cache.cached - 1] + cache.cache[cache.cached - 2];
     }
     return cache.cache[i];
 }
 
 int main(int argc, char **argv) {
     // TODO: 初始化缓存结构体，使计算正确
+    FibonacciCache fib = { {0, 1}, 2 };
     // 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;
     ASSERT(fibonacci(fib, 10) == 55, "fibonacci(10) should be 55");
     std::cout << "fibonacci(10) = " << fibonacci(fib, 10) << std::endl;
     return 0;

exercises/11_method/main.cpp

@@ -6,7 +6,7 @@ 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];
@@ -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},2};
     ASSERT(fib.get(10) == 55, "fibonacci(10) should be 55");
     std::cout << "fibonacci(10) = " << fib.get(10) << std::endl;
     return 0;

exercises/12_method_const/main.cpp

@@ -5,7 +5,9 @@
 struct Fibonacci {
     int numbers[11];
     // TODO: 修改方法签名和实现，使测试通过
-    int get(int i) {
+    constexpr int get(int i) const{
+        // const=我承诺不改对象；constexpr我可以在编译时运行
+        return numbers[i];
     }
 };
 

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];

exercises/14_class_destruct/main.cpp

@@ -10,15 +10,22 @@ class DynFibonacci {
     int cached;
 
 public:
-    // TODO: 实现动态设置容量的构造器
-    DynFibonacci(int capacity): cache(new ?), cached(?) {}
+    // TODO: 实现动态设置容量的构造器。初始化列表
+    DynFibonacci(int capacity): 
+        cache(new size_t[capacity]), cached(2) 
+    {
+        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) {
+        for (; cached <= i; ++cached) {
             cache[cached] = cache[cached - 1] + cache[cached - 2];
         }
         return cache[i];

exercises/15_class_clone/main.cpp

@@ -10,17 +10,30 @@ 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(2) {
+        cache[0] = 0;
+        cache[1] = 1;
+        }
+
     // TODO: 实现复制构造器
-    DynFibonacci(DynFibonacci const &) = delete;
+    DynFibonacci(DynFibonacci const &others) 
+    : cache(new size_t[others.cached]), 
+      cached(others.cached) {
+        for (int i = 0; i < cached; ++i) {
+            cache[i] = others.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];

exercises/16_class_move/main.cpp

@@ -15,21 +15,48 @@ 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(2) {
+            cache[0]=0;
+            cache[1]=1;
+        };
 
-    // TODO: 实现移动构造器
-    DynFibonacci(DynFibonacci &&) noexcept = delete;
+    // TODO: 实现移动构造器，Move Constructor
+    DynFibonacci(DynFibonacci && others) noexcept 
+    : cache(others.cache),
+        cached(others.cached){
+            // “偷走”资源后，把原对象的指针置为空，防止原对象析构时删掉这块内存
+            others.cache = nullptr;
+            others.cached = 0;
+    }
 
-    // TODO: 实现移动赋值
+    // TODO: 实现移动赋值, Move Assignment
     // NOTICE: ⚠ 注意移动到自身问题 ⚠
-    DynFibonacci &operator=(DynFibonacci &&) noexcept = delete;
+    DynFibonacci &operator=(DynFibonacci &&others) noexcept
+    {
+        // 检查是否是自己给自己赋值
+        if (this != &others){
+            // 释放自己原有的内存
+            delete[] cache;
+            // “偷走”资源
+            cache = others.cache;
+            cached = others.cached;
+            // 把原对象置为空，防止析构时删除内存
+            others.cache = nullptr;
+            others.cached = 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];

exercises/17_class_derive/main.cpp

@@ -45,14 +45,14 @@ struct B : public A {
 };
 
 int main(int argc, char **argv) {
-    X x = X(1);
-    A a = A(2);
-    B b = B(3);
+    X x = X(1);  //造了一个 X，里面是 1
+    A a = A(2);  //造一个 A(2)，通常不会多一次拷贝
+    B b = B(3);  //打印 B(1, X(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(A) + sizeof(X), "B is an A with an X");
 
     i = 0;
     std::cout << std::endl