docs: answer question 1 (#323)

src/群友提交/第01题/youmu_lew.cpp

@@ -0,0 +1,20 @@
+#include <iostream>
+#include <vector>
+#include <functional>
+
+template<typename T, typename Func>
+std::vector<T>& operator|(std::vector<T>& v, Func func) {
+    for (auto& i : v) {
+        func(i);
+    }
+    return v;
+}
+
+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;
+}
+
+// 预期结果： 1 4 9