程序阅读题 : 阅读以下程序: #include using namespace std; class Number { public: Number(int _n, int *_vec): n(_n) { vec = new int[n]; for(int i=0; i vec[i] = _vec[i]; } Number(const Number &rn): n(rn.n) { vec = new int[n]; for(int i=0; i vec[i] = rn.vec[i]; } int& at(int idx) { return vec[idx]; } int size() const { return n; } void print() const { for(int i=0; i cout< } private: int *vec; int n; }; int main() { int a[3] = {12, 20, 33}, b[3] = {45, 63, 22}; Number nb1(3, a), nb2(3, b), nb3(nb1); nb2 = nb1; nb2.at(1) += 10; nb3.at(2) = 88; nb1.print(); nb2.print(); nb3.print(); return 0; } 程序执行后的输出结果为 ________________________