0001 template <typename T> //单元素插入
0002 void Vector<T>::insert(Rank r, const T& e) //0 <= r <= _size
0003    { insert(r, &e, 0, 1); } //insert, O(n+1-r)
0004 
0005 template <typename T> //T为基本类型，或已重载赋值操作符'='；S <> this
0006 void Vector<T>::insert(Rank r, const T* A, Rank lo, Rank hi) { //将A[lo,hi)插至[r]
0007    Rank d = hi-lo;  expand(d); //若必要，先扩容：确保足以新增d个元素
0008    for (Rank i = _size-1; i != r-1; i--) //长度为n-r的后缀：自后向前地后移
0009       _elem[i + d] = _elem[i]; //O(n-r)
0010    copy(r, A, lo, hi);  _size += d; //插入d个元素，O(d)
0011 } //insert, O(n+d-r)