hw03

main.cpp

@@ -3,53 +3,71 @@
 #include <variant>
 
 // 请修复这个函数的定义：10 分
-std::ostream &operator<<(std::ostream &os, std::vector<T> const &a) {
-    os << "{";
-    for (size_t i = 0; i < a.size(); i++) {
-        os << a[i];
-        if (i != a.size() - 1)
-            os << ", ";
-    }
-    os << "}";
-    return os;
+template <class T>
+std::ostream &operator<<(std::ostream &os, std::vector<T> const &a)
+{
+	os << "{";
+	for (size_t i = 0; i < a.size(); i++)
+	{
+		os << a[i];
+		if (i != a.size() - 1)
+			os << ", ";
+	}
+	os << "}";
+	return os;
 }
 
 // 请修复这个函数的定义：10 分
 template <class T1, class T2>
-std::vector<T0> operator+(std::vector<T1> const &a, std::vector<T2> const &b) {
-    // 请实现列表的逐元素加法！10 分
-    // 例如 {1, 2} + {3, 4} = {4, 6}
+auto operator+(std::vector<T1> const &a, std::vector<T2> const &b)
+{
+	// 请实现列表的逐元素加法！10 分
+	// 例如 {1, 2} + {3, 4} = {4, 6}
+	using T0 = decltype(a[0] + b[0]);
+	int len = std::min(a.size(), b.size());
+	std::vector<T0> v(len);
+	for (int i = 0; i < len; i++)
+		v[i] += a[i] + b[i];
+	return v;
 }
 
 template <class T1, class T2>
-std::variant<T1, T2> operator+(std::variant<T1, T2> const &a, std::variant<T1, T2> const &b) {
-    // 请实现自动匹配容器中具体类型的加法！10 分
+std::variant<T1, T2> operator+(std::variant<T1, T2> const &a, std::variant<T1, T2> const &b)
+{
+	// 请实现自动匹配容器中具体类型的加法！10 分
+	return std::visit([](auto const &a, auto const &b)
+					  { return std::variant<T1, T2>(a + b); },
+					  a, b);
 }
 
 template <class T1, class T2>
-std::ostream &operator<<(std::ostream &os, std::variant<T1, T2> const &a) {
-    // 请实现自动匹配容器中具体类型的打印！10 分
+std::ostream &operator<<(std::ostream &os, std::variant<T1, T2> const &a)
+{
+	// 请实现自动匹配容器中具体类型的打印！10 分
+	std::visit([&](auto const &a){ os << a; },a);
+	return os;
 }
 
-int main() {
-    std::vector<int> a = {1, 4, 2, 8, 5, 7};
-    std::cout << a << std::endl;
-    std::vector<double> b = {3.14, 2.718, 0.618};
-    std::cout << b << std::endl;
-    auto c = a + b;
+int main()
+{
+	std::vector<int> a = {1, 4, 2, 8, 5, 7};
+	std::cout << a << std::endl;
+	std::vector<double> b = {3.14, 2.718, 0.618};
+	std::cout << b << std::endl;
+	auto c = a + b;
 
-    // 应该输出 1
-    std::cout << std::is_same_v<decltype(c), std::vector<double>> << std::endl;
+	// 应该输出 1
+	std::cout << std::is_same_v<decltype(c), std::vector<double>> << std::endl;
 
-    // 应该输出 {4.14, 6.718, 2.618}
-    std::cout << c << std::endl;
+	// 应该输出 {4.14, 6.718, 2.618}
+	std::cout << c << std::endl;
 
-    std::variant<std::vector<int>, std::vector<double>> d = c;
-    std::variant<std::vector<int>, std::vector<double>> e = a;
-    d = d + c + e;
+	std::variant<std::vector<int>, std::vector<double>> d = c;
+	std::variant<std::vector<int>, std::vector<double>> e = a;
+	d = d + decltype(d)(c) + e;
 
-    // 应该输出 {9.28, 17.436, 7.236}
-    std::cout << d << std::endl;
+	// 应该输出 {9.28, 17.436, 7.236}
+	std::cout << d << std::endl;
 
-    return 0;
+	return 0;
 }