template<class T>
class MyVector {
    T* start;
    T* finish;
    T* end_of_storage;
public:
    using iterator = T*;

    iterator begin() { return start; }
    iterator end() { return finish; }
    
    void push_back(const T& v) {
        if (finish == end_of_storage) {
            // 重新分配、更大容量，并搬移元素
        }
        new (finish) T(v);
        ++finish;
    }

};