初步完成的c++二维矩阵容器

小小的二维矩阵，用到了模板、智能指针，列表等 

#include <iostream>
#include <memory>
#include <vector>

using namespace std;


template<typename T>
class Array2D {
public:
    Array2D() {};
    Array2D(int m, int n, T value):_m(m),_n(n) {
        grid = make_shared<vector<shared_ptr<vector<T>>>>(m, 
            make_shared<vector<T>>(n, value));
       
    }
    Array2D(Array2D& array2d) {
        _m = array2d.getM();
        _n = array2d.getN();
        grid = make_shared<vector<shared_ptr<vector<T>>>>(_m,
            make_shared<vector<T>>(_n, 0));
        for (int i = 0; i < _m; i++) {
            for (int j = 0; j < _n; j++)
                grid->at(i)->at(j) = array2d.getValue(i, j);
                
        }
    }
    ~Array2D() {};
    inline int getM() { return _m; }
    inline int getN() { return _n; }
    T getValue(int i, int j){
        return grid->at(i)->at(j);
    }
private:
    int _m, _n;
    shared_ptr<vector<shared_ptr<vector<T>>>>grid;
    
};

int main()
{
    std::cout << "Hello World!\n";
    Array2D<double> mat(300, 200, 1.5);
    auto mat2 (mat);
    for (int i = 0; i < mat2.getM(); i++) {
        for (int j = 0; j < mat2.getN(); j++)
            cout << mat2.getValue(i,j) << " ";
    }
}