涼風青葉提交第1，2，3题

src/群友提交/第01题/涼風青葉.cpp

@@ -0,0 +1,16 @@
+#include<iostream>
+#include<vector>
+#include<functional>
+
+template<typename T, typename Formatter>
+T &operator|(T &arr, const Formatter &func) {
+    std::for_each(std::begin(arr), std::end(arr), func);
+    return arr;
+}
+
+int main() {
+    std::vector v{ 1, 2, 3 };
+    std::function f{ [](const int &i) {std::cout << i << ' '; } };
+    auto f2 = [](int &i) {i *= i; };
+    v | f2 | f;
+}

src/群友提交/第02题/涼風青葉.cpp

@@ -0,0 +1,29 @@
+#include<iostream>
+#include<numbers>
+#include<format>
+
+struct Formatter {
+    const std::string_view fmt;
+
+    Formatter(const char *s) : fmt(s) { }
+
+    template<typename ...T>
+    std::string operator()(const T &...args) const {
+        return std::vformat(fmt, std::make_format_args(args...));
+    }
+};
+
+Formatter operator""_f(const char *s, std::size_t) {
+    return { s };
+}
+
+int main() {
+    std::cout << "乐 :{} *\n"_f(5);
+    std::cout << "乐 :{0} {0} *\n"_f(5);
+    std::cout << "乐 :{:b} *\n"_f(0b01010101);
+    std::cout << "{:*<10}"_f("卢瑟");
+    std::cout << '\n';
+    int n{};
+    std::cin >> n;
+    std::cout << "π：{:.{}f}\n"_f(std::numbers::pi_v<double>, n);
+}

src/群友提交/第03题/涼風青葉.cpp

@@ -0,0 +1,23 @@
+#include<iostream>
+#include<format>
+
+struct Frac {
+    int a, b;
+};
+
+template<>
+struct std::formatter<Frac> : std::formatter<char> {
+    auto format(const Frac &arg, std::format_context &ctx) const {
+        return std::format_to(ctx.out(), "{}/{}", arg.a, arg.b);
+    }
+};
+
+template<typename T, typename ...U>
+void print(T fmt, U ...args) {
+    std::cout << std::vformat(fmt, std::make_format_args(args...));
+}
+
+int main() {
+    Frac f{ 1, 10 };
+    print("{}", f);
+}