HackerRank, c++, Operator Overloading

간단한 operator overloading 문제,

2중 vector를 쓸 때에는, 2차원 vector를 따로 만들고 넣어 줘야한다.

배열처럼 바로 접근 하면 segmentation fault,

class Matrix{
public:
    vector< vector<int>> a;
    
    Matrix operator+(Matrix y){
        Matrix *newMatrix = new Matrix();
        for(unsigned int i = 0 ; i < a.size(); i++)
        {
            vector<int> vect;
            for(unsigned int j = 0; j < a[i].size(); j++)
            {
                vect.push_back(a[i][j] + y.a[i][j]);
            }
            newMatrix->a.push_back(vect);
        }
        return *newMatrix;
    }
};