private:
        vector < vector <int> > Matrix;
        vector < vector <int> > temp_m;
        vector <int> elements
        string input;
        int value;
function()
{
//Initialize Both Matrices (one which holds the puzzle and the
//other which holds the values between 1 and 9
//Create a vector of vectors:
for(int i = 0; i < 9; i++)
    elements.push_back(i+1);
for(int i = 0; i < 9; i++)
    Matrix[i].push_back(elements);  //ERROR HERE
}

class MyClass
{
public:
    MyClass::MyClass()
      : row(9,0), elements(9)
    {
    }

private:
        vector < vector <int> > Matrix;
        vector < vector <int> > temp_m;
        vector <int> row;
        vector <int> elements;
        string input;
        int value;
}

A::A() : row(9, 0), elements(9) {}

private:
    vector<int> row;
    vector<int> elements;