Operator Overloading

Classes define new types in C++. Types in C++ not only interact by means of constructions and assignments but also via operators. For example:

int a=2, b=1, c;
c = b + a;

The result of variable c will be 3.
Similarly, classes can also perform operations using operator overloading. Operators are overloaded by means of operator functions, which are regular functions with special names. Their name begins with the operator keyword followed by the operator sign that is overloaded. The syntax is:

type operator sign (parameters) { /*... body ...*/ }

The sum of first matrix and the second matrix is the matrix given in the output. 

#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;
}
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;
}

Sample Input

1
2 2
2 2 2 2
1 2 3 4

Sample Output

3 4 
5 6

Explanation

The sum of first matrix and the second matrix is the matrix given in the output.