HackerRank Operator Overloading solution in c++ programming

In this HackerRank Operator Overloading problem in c++ programming language, You are given a main() function that takes a set of inputs to create two matrices and prints the result of their addition. You need to write the class Matrix which has a member an of type vector<vector<int> >. You also need to write a member function to overload the operator +. The function's job will be to add two objects of Matrix-type and return the resultant Matrix.

HackerRank operator overloading problem solution in c++ programming.

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

class Matrix{

public:
vector<vector<int> > a;

Matrix & operator + (const Matrix &y) {

    for (int m=0; m<y.a.size(); ++m) {
        for (int n=0; n<y.a[0].size(); ++n) {
            this->a[m][n] = this->a[m][n] + y.a[m][n];
        }
    }

    return *this;
}
};

int main () {
   int cases,k;
   cin >> cases;
   for(k=0;k<cases;k++) {
      Matrix x;
      Matrix y;
      Matrix result;
      int n,m,i,j;
      cin >> n >> m;
      for(i=0;i<n;i++) {
         vector<int> b;
         int num;
         for(j=0;j<m;j++) {
            cin >> num;
            b.push_back(num);
         }
         x.a.push_back(b);
      }
      for(i=0;i<n;i++) {
         vector<int> b;
         int num;
         for(j=0;j<m;j++) {
            cin >> num;
            b.push_back(num);
         }
         y.a.push_back(b);
      }
      result = x+y;
      for(i=0;i<n;i++) {
         for(j=0;j<m;j++) {
            cout << result.a[i][j] << " ";
         }
         cout << endl;
      }
   }  
   return 0;
}

Second solution

// overloading operators example
#include <iostream>
#include <vector>
using namespace std;

class Matrix {
    public:
        vector<vector<int> > a;
        Matrix operator + (const Matrix&);
};

Matrix Matrix::operator+ (const Matrix& param) {
    Matrix temp;
    int n = a.size(),i,j;
    int m = a[0].size();
    for(i=0;i<n;i++) {
        vector<int> b;
        for(j=0;j<m;j++) {
            b.push_back(param.a[i][j]+a[i][j]);
        }
        temp.a.push_back(b);
    }
    return temp;
}

int main () {
    int cases,k;
    cin >> cases;
    for(k=0;k<cases;k++) {
        Matrix x;
        Matrix y;
        Matrix result;
        int n,m,i,j;
        cin >> n >> m;
        for(i=0;i<n;i++) {
            vector<int> b;
            int num;
            for(j=0;j<m;j++) {
                cin >> num;
                b.push_back(num);
            }
            x.a.push_back(b);
        }
        for(i=0;i<n;i++) {
            vector<int> b;
            int num;
            for(j=0;j<m;j++) {
                cin >> num;
                b.push_back(num);
            }
            y.a.push_back(b);
        }
        result = x+y;
        for(i=0;i<n;i++) {
            for(j=0;j<m;j++) {
                cout << result.a[i][j] << " ";
            }
            cout << "\n";
        }
    }  
    return 0;
}